If the applied field E0 has an arbitrary direction, then the induced dipole moment can be easily found from the superposition

Where, are the field components with respect to the principal axes of the ellipsoid. In scattering problems, the coordinate axes are usually chosen to be fixed with respect to the incident beam. Let x" y" z" be such a coordinate system where the propagation direction is parallel to the z-axis". If the incident light

x" is polarized, then from the optical theorem we have:

To carry out calculations using formula (2.2), it is necessary to write out the p components with respect to the axes drawn by dashed lines. Equality (2.1) can be written in matrix form:

We write column vectors and matrices in a more compact form in accordance with the following notation:

With this notation, 2.3 takes the following form:

The components of an arbitrary vector F are transformed in accordance with the formula:

Where, etc. As a result, from (2.5) and transformation (2.6) we have:

where, due to the orthogonality of the coordinate axes, the matrix inverse to is the transposed matrix. Thus, the polarizability of an ellipsoid is a Cartesian tensor; if its components in the principal axes are given, then its components in the rotated coordinate axes can be determined by formula (2.8). The absorption cross section for incident - polarized light is determined simply by the formula:

Where. Similarly, if the incident light is polarized, then

If the vector scattering amplitude

for a dipole illuminated by -polarized light, substitute into the cross section equation, then we obtain the scattering cross section

Where we used the matrix identity. A similar expression holds for the scattering cross section and for incident polarized light.

Application.

Polarized light was proposed to be used to protect the driver from the blinding light of the headlights of an oncoming car. If film polaroids with a transmission angle of 45o are applied to the windshield and headlights of a car, for example, to the right of the vertical, the driver will clearly see the road and oncoming cars illuminated by their own headlights. But for oncoming cars, the polaroids of the headlights will be crossed with the polaroid of the windshield of this car, and the headlights of oncoming cars will go out.

Two crossed polaroids form the basis of many useful devices. Light does not pass through crossed polaroids, but if you place an optical element between them that rotates the plane of polarization, you can open the way for light. This is how high-speed electro-optical light modulators are arranged. They are used in many technical devices - in electronic rangefinders, optical communication channels, laser technology.

The so-called photochromic glasses are known, darkening in bright sunlight, but not able to protect the eyes with a very fast and bright flash (for example, during electric welding) - the darkening process is relatively slow. Polarized glasses have an almost instant "reaction" (less than 50 microseconds). The light of a bright flash enters miniature photodetectors (photodiodes), which supply an electrical signal, under the influence of which the glasses become opaque.

Polarized glasses are used in stereo cinema, which gives the illusion of three-dimensionality. The illusion is based on the creation of a stereo pair - two images taken at different angles, corresponding to the angles of view of the right and left eyes. They are considered so that each eye sees only the image intended for it. The image for the left eye is projected onto the screen through a polaroid with a vertical transmission axis, and for the right eye with a horizontal axis, and they are precisely aligned on the screen. The viewer looks through polaroid glasses, in which the axis of the left polaroid is vertical, and the right one is horizontal; each eye sees only “its own” image, and a stereo effect arises.

For stereoscopic television, the method of rapidly alternating dimming of glasses is used, synchronized with the change of images on the screen. Due to the inertia of vision, a three-dimensional image arises.

Polaroids are widely used to dampen glare from glass and polished surfaces, from water (the light reflected from them is highly polarized). Polarized and light screens of liquid crystal monitors.

Polarization methods are used in mineralogy, crystallography, geology, biology, astrophysics, meteorology, and in the study of atmospheric phenomena.

UDC 539.18

DIFFERENTIAL SECTION AND VECTOR ANALYZING POWER OF ELASTIC DP SCATTERING AT 2 GeV

A.A. Terekhin1),2)*, V.V. Glagolev2), V.P. Ladygin2), N.B. Ladygina2)

1) Belgorod State University, st. Studencheskaya, 14, Belgorod, 308007, Russia 2) Joint Institute for Nuclear Research, st. Joliot-Curie, b, Dubna, 141980, Russia, *e-mail: [email protected]

Annotation. The results of measurements and the procedure for processing data on the angular dependence of the vector analyzing power Ay and the cross section for the elastic dp scattering reaction at an energy of 2 GeV are presented. The results obtained are in good agreement with world experimental data and with theoretical calculations performed in the framework of the relativistic model of multiple scattering.

Keywords: elastic dp scattering, differential cross section, analyzing power.

Introduction

In connection with the active study of the nature of nuclear forces and non-nucleon degrees of freedom, interest in the simplest nuclear reactions and their polarization characteristics has recently increased greatly. The study of polarization effects is necessary for solving many modern problems of nuclear physics and elementary particle physics. The structure of light nuclei has been intensively studied in the last few decades with the help of both electromagnetic and hadronic probes. A significant amount of experimental data has been accumulated on the spin structure of light nuclei at small internucleon distances. Reactions p(d,p)d, 3He(d,p)4He, or 3Hv(d, 3d)^ are the simplest processes with large momentum transfer. They can be used as a tool for studying the structure of the deuteron and 3^, as well as the mechanisms of interaction of nucleons at short distances.

The deuteron has a spin equal to 1, which gives ample opportunities in carrying out numerous polarization experiments that allow obtaining new information about the behavior of various independent observables. In contrast to the static properties of the deuteron (binding energy, root-mean-square radius, magnetic moment), its structure at short distances has been studied much less well. The high-momentum components in the deuteron wave functions correspond to the region of small internucleon distances (r^m< 1 Фм), где нуклоны уже заметно перекрываются и теряют свою индивидуальность. Изучение поведения поляризационных наблюдаемых, чувствительных к спиновой структуре дейтрона на малых межнуклонных расстояниях, позволит

obtain information about the manifestation of non-nucleon degrees of freedom and relativistic effects.

In recent years, a number of studies of polarization observables of the dp-elastic scattering reaction have been carried out in various energy ranges. The aim of the research is to study polarization observables at intermediate and high energies. For 270 MeV, data were obtained on the reaction cross section, the polarization transfer coefficients from the deuteron to the proton Kc, the deuteron vector Ay and tensor A^ analyzing abilities, and the polarization Py. The cross section and vector analyzing power are well described by Faddeev calculations based on new MM potentials using the Tucson-Melbourne three-nucleon force. On the other hand, the tensor analyzing power Ay, the transmission coefficients K^, and the polarization Py are not described by these calculations. Also for 270 MeV, data were obtained on the cross section, Ау and А^ for the angular range in cm. Comparison with Faddeev's calculations shows good agreement between all components of the analyzing abilities. A noticeable discrepancy is observed in the cross section (30%) near the angle β* = 120°.

Rice. 1. Distribution of events over the scattering angle in*

As the energy increases, relativistic effects and non-nucleon degrees of freedom begin to play an increasingly important role. Another important aspect is that the analyzing abilities of the reaction are important enough for efficient polarimetry in a wide range of deuteron energies. Recently, data have been obtained on the analyzing abilities of Ay and A^ at 880 MeV in the angular range of 60°< в* < 140° .

1. Experiment

Data collection was carried out in a series of experiments on a 100 cm hydrogen chamber exposed to the extracted deuteron beam of the synchrophasotron with an energy of 2 GeV. The use of bubble chambers is noteworthy in that the observation can be carried out under conditions of 4n geometry. A characteristic feature of the hydrogen chamber is that

that the interaction occurs only with protons (the so-called clean target). In addition, the chamber is in a magnetic field, which helps to identify the mass of secondary particles.

Rice. 2. Distributions over the azimuthal angle p for different angles

Polaris source of polarized deuterons provided deuterons with theoretical values ​​of vector and tensor polarizations: (Pz, Pzz) = (+2/3, 0), (-2/3, 0) - polarized modes and (0, 0) - unpolarized fashion. These states alternated in accelerator cycles, the corresponding marks were transmitted to the recording equipment of the camera. Events were selected on viewing tables and measured on semi-automatic and HPD machines at JINR. Mathematical processing was carried out using the adapted programs THRESH (geometric reconstruction) and GRIND (kinematic identification) of CERN, as well as a chain of auxiliary programs for selecting reactions and recording the results on the DST (summary results tape). Events were classified according to the results of the kinematic identification program (GRIND) using data from the assessment of ionization losses. Service information necessary for subsequent processing was imprinted into each frame of the film using an information board. In particular, when working in a beam of polarized deuterons, information about the state of polarization that came in each cycle of acceleration from the source of polarized particles "POLARIS" was imprinted in coded form. In our case - vector. This information was stored for each event and on the DST.

The deuteron polarization was calculated from an analysis of the azimuthal asymmetry of recoil nucleons in quasi-free scattering by a proton target. The analysis was carried out both for all events and for events in the region of small transferred impulses.

owls (to< 0.065 ОеУ/с), т.к. в последней дейтронная и нуклонная векторные поляризации приблизительно равны. Полученное значение дейтронной поляризации равнялось Р? = 0.488 ± 0.061 .

2. Data processing

The values ​​for the vector analyzing power Ay were found by processing events corresponding to different deuteron beam polarization states (polarization modes 1 and 2 correspond to such states). The distribution over the scattering angle β* in the center-of-mass system is shown in Fig. . one.

Rice. Fig. 3. Distribution of the quantity R over the azimuthal angle p for scattering angles of 12°< в < 14°

The working part of the spectrum was divided into successive intervals (bins). The number of events in each interval was normalized to the width of the last one. For each interval, a distribution over the azimuth angle p was constructed. For small scattering angles θ*, event losses are significant (Fig. 2), due to the fact that, at the viewing stage, tracks of recoil protons with momenta less than 80 MeV/c are no longer visible in the chamber. In addition, there are azimuthal losses associated with the camera's optics. In this area, intervals corresponding to lost events were excluded. Elimination by intervals was carried out symmetrically with respect to the values ​​p = 0o and p = 180°. The remaining events were used to calculate the differential cross section and the analyzing power.

For each selected interval along the angle, the value of R was calculated:

where N1 and N2 are the numbers of events for spin mode values ​​1 and 2, respectively. Approximation of the obtained data was carried out by the function vidar0+p1 wt(p). On fig. 3, as a

As an example, the distribution over the azimuth angle is given for angles of 12°< в* < 14° в с.ц.м.

For each interval of the distribution over β*, the values ​​of the parameters p0 and p1 of the approximating function p0 + p1 wt(p) were obtained. The parameter p0 has the meaning of the so-called false asymmetry. The estimated value of false asymmetry, obtained by approximating the values ​​of the p0 parameter, does not exceed 5% and is p0 = -0.025 ± 0.014. The parameter p1 is related to the analyzing ability of y by the expression:

Rice. 4. Analyzing power Ay of the dp-elastic scattering reaction at an energy of 2 GeV.

Solid symbols are the results of this experiment, open symbols are the data obtained in ANL. Line - results of calculations within the framework of the multiple scattering model

The obtained values ​​for the vector analyzing power y are shown in fig. 4. They agree with sufficient accuracy with the data obtained in ANL and with the calculations of the theory.

Events obtained from both polarized and unpolarized deuteron beams were used to calculate the cross section for the dp-elastic scattering reaction. An analysis was made of the distribution over the cosine of the scattering angle θ* in the center-of-mass system. For each interval Dv*, the corresponding interval Acosv* was taken (Fig. 5.6). Then normalization was carried out to the width of the interval A cos in*. The reaction cross section was calculated by the formula:

where the vector polarization of the beam is py = 0.488 ± 0.061 .

where A = 0.0003342 ± 0.0000007 [mb/event] is the millibarn equivalent of the event , A cos in* is the width of the interval in the distribution of the number of events over the cosine of the scattering angle in*.

Rice. B. Distribution of events over scattering angle O*

Rice. b. Distribution of events by cos О*

As the scattering angle θ* increases, the deviation from isotropy decreases. At β* > 20°, the distribution becomes isotropic. In the distribution over the azimuthal angle p, bins corresponding to lost events were excluded. The exclusion was carried out within the same limits as in the calculation of the analyzing power Ay.

Rice. 7. Differential cross sections in cm. Solid symbols - results of this experiment, open symbols - work data, solid line - results

theoretical calculations

The obtained values ​​of the reaction cross section depending on the angle θ* were compared with

world data, as well as with theoretical calculations performed in the framework of the relativistic model of multiple scattering and, as can be seen from Fig. 7 are in good agreement.

Conclusion

Values ​​are obtained for the vector analyzing power and the cross section for the elastic dp scattering reaction at an energy of 2 GeV in an angular range of 10°< в* < 34° в с.ц.м. Проведено сравнение с мировыми данными и с теоретическими расчетами, выполненными в рамках релятивистской модели многократного рассеяния. Выявлено хорошее согласие теоретических и экспериментальных значений.

Literature

1 Day D. et al. // Phys. Rev. Lett. - 1979. - 43. - P.1143.

2. Lehar F. // RNP: from Hundreds of MeV to TeV. 2001. V. 1. P. 36.

3. Sakai H. et al. Precise measurement of dp elastic scattering at 270 MeV and three-nucleon force effects // Phys Rev Lett. - 2000. - 162. - P.143.

4. Coon S.A. et al. // Nucl.Phys. - 1979. - A317. - P.242.

5. Sakamoto N. et al. Measurement of the vector and tensor analyzing powers for the dp elastic scattering at Ed = 270 MeV // Phys. Lett. - 1996. - B.367. - P.60-64.

6. Kurilkin P.K. et al. Measurement of the vector and tensor analyzing powers in dp elastic scattering at the energy of 880 MeV // European Physical Journal. special topics. - 2008. -162. - P.137-141.

7. Anishchenko, et al. AIP Conf. Proc. - 95 (1983). - P.445.

8. CERN T.C. Program Library, sec. THRESH, 1.3. - 1966.

9. CERN T.C. Program Library, sec. GRIND, 30.10. - 1968.

10. Glagolev V.V. et al. The deuteron D-state probability // Zeitchrift fur Physik. - 1996. - A 356. - P.183-186.

11. Glagolev V.V. Optics of a meter-long hydrogen bubble chamber // JINR preprint.

12. Haji Saica M., Phys. Rev. - 1987. - C36. - P.2010.

13. Ladygina N.B. Measurement of the vector and tensor analyzing powers in dp elastic scattering at the energy of 880 MeV // European Physical Journal. special topics. - 2008. - 162. -P.137-141.

14. Bugg D.V. et al. Nucleon-Nucleon Total Cross Sections from 1.1 to 8 GeV/c // Phys. Rev. Lett. - 1996. - 146. - P.980-992.

15. Bennett G. W. et al. Proton-deuteron scattering at 1 BeV, Phys. Rev. Lett. - 1976. - 19. - P.387-390.

DIFFERENTIAL CROSS SECTION AND VECTOR ANALYZING POWER IN D-P ELASTIC SCATTERING AT 2.0 GeV A.A. Terekhin 1)’2)*, V.V. Glagolev2), V.P. Ladygin2), N.B. Ladygina2)

Belgorod State University,

Studencheskaja St., 14, Belgorod, 308007, Russia

2) Joint Institute for Nuclear Researches,

Zholio-Kjuri St., 6, Dubna, 141980, Russia, * e-mail: [email protected]

abstract. The results of measurements as well as handling procedure for the data on the angular dependence of the vector analyzing powers Ay and differential cross section for dp-elastic scattering at Ed = 2 GeV are reported. The obtained data are in good agreement with the existing data and theoretical calculations made in the framework of the relativistic multiple scattering model.

Key words: elastic dp-scattering, differential cross-section, analysis possibility.

480 rub. | 150 UAH | $7.5 ", MOUSEOFF, FGCOLOR, "#FFFFCC",BGCOLOR, "#393939");" onMouseOut="return nd();"> Thesis - 480 rubles, shipping 10 minutes 24 hours a day, seven days a week and holidays

Isupov Alexander Yurievich. Measurements of the tensor analyzing ability T20 in the reaction of deuteron fragmentation into pions at zero angle and software development for data acquisition systems for installations on polarized beams: dissertation ... Candidate of Physical and Mathematical Sciences: 01.04.16, 01.04.01 .- Dubna, 2005. - 142 p.: ill. RSL OD, 61 06-1/101

Introduction

I Setting up the experiment 18

1.1 Motivation 18

1.2 Experimental setup 20

1.3 Methodological measurements and modeling 24

1.4 Organization and principle of operation of the trigger 33

II Software 40

II.1 Introductory remarks 40

II.2 Data collection and processing system qdpb 42

II.3 Configurable views of data and hardware 56

II.4 Session-dependent means of data representation. 70

II.5 DAQ system SPHERE 74

II. 6 Polarimeter Data Acquisition Systems 92

III. Experimental results and discussion 116

III.1 Analysis of sources of systematic errors 116

III.2 Experimental data 120

Sh.3. Discussion of experimental data 127

Conclusion 132

Literature 134

Introduction to work

B.1 Introduction

The dissertation paper presents the experimental results of measurements of the tensor analyzing power of Tr in the reaction of fragmentation of tensor polarized deuterons into cumulative (sub-threshold) pions. The measurements were carried out by the SPHERE collaboration on a beam of tensor polarized deuterons at the accelerator complex of the High Energy Laboratory of the Joint Institute for Nuclear Research (LHE JINR, Dubna, Russia). The study of polarization observables provides more detailed information, compared to reactions with non-polarized particles, on the interaction Hamiltonian, reaction mechanisms, and the structure of the particles involved in the reaction. To date, the question of the properties of nuclei at distances smaller than or comparable to the size of a nucleon has not been adequately studied both from the experimental and theoretical points of view. Of all the nuclei, the deuteron is of particular interest: firstly, it is the most studied nucleus from both experimental and theoretical points of view. Secondly, for the deuteron, as for the simplest nucleus, it is easier to understand the reaction mechanisms. Third, the deuteron has a nontrivial spin structure (spin equal to 1 and a nonzero quadrupole moment), which provides wide experimental possibilities for studying spin observables. The measurement program, within the framework of which the experimental data presented in the dissertation work were obtained, is a natural continuation of studies of the structure of atomic nuclei in reactions with the production of cumulative particles in the collision of unpolarized nuclei, as well as polarization observables in the deuteron decay reaction. The experimental data presented in the dissertation work make it possible to advance in understanding the spin structure of the deuteron at small internucleon distances and supplement the information on the structure of the deuteron obtained in experiments with a lepton probe and in the study of the breakup reaction of tensor polarized deuterons, and therefore seem to be relevant. To date, the data presented in the dissertation work are the only ones, since such studies require beams of polarized deuterons with an energy of several GeV, which at present and in the next few

years will be available only at the JINR LHE accelerator complex, where it is natural to continue research in this direction. The mentioned data were obtained as part of an international collaboration, were reported at a number of international conferences, and also published in peer-reviewed journals.

Further in this chapter, we present the information about cumulative particles necessary for further presentation, the definitions used in the description of polarization observables, and also give a brief review of the results known in the literature on the deuteron breakup reaction.

B.2 Cumulative particles

Studies of the regularities of the birth of cumulative particles have been carried out since the beginning of the seventies of the XX century, , , , , , , , , , , , . The study of reactions with the production of cumulative particles is interesting in that it provides information about the behavior of the high-momentum (> 0.2 GeV/c) component in fragmenting nuclei. These large internal momenta correspond to small ones (xx > 1, where the cross sections become very small.

First of all, let us define what will be further understood by the term "cumulative particle" (see, for example, the references therein). Particle with, born in reaction:

Ag + AP -Ї- c + x, (1)

is called "cumulative" if the following two conditions are met:

the particle c is produced in a kinematic region inaccessible in the collision of free nucleons having the same momentum per nucleon as the nuclei A/ and Ats in reaction (1);

particle with belongs to the fragmentation region of one of the colliding particles, i.e. must be done either

\YAt-Yc\^\YAn-Yc\., (2)

where Yi is the speed of the corresponding particle z. It follows from the first condition that at least one of the colliding particles must be a nucleus. It can be seen from the second condition that the colliding particles enter this definition asymmetrically. In this case, the particle that lies closer to the cumulative one in terms of speed will be called the fragmenting particle, and the other of the colliding particles will be called the particle on which fragmentation occurs. Usually, experiments with the production of cumulative particles are set up in such a way that the detected particle lies outside the rapidity interval [Vpn, )%]. In this case, the second condition reduces to the requirement of a sufficiently large collision energy:

\UUp - Atwith\ « \YAl~ Yc\ = |U L// - Yc\ + \YAn-YAl\ . (4)

It follows from experimental data (see, for example, , , , , , , , ) that for experiments on a fixed target, the shape of the spectrum of cumulative particles weakly depends on the collision energy, starting from the energies of incident particles Th > 3-4 GeV. This statement is illustrated in Fig. 1, reproduced from , which shows the dependences on the energy of the incident proton: (b) the ratio of the outputs of pions of different signs 7r~/tr + and (a) the parameter of the inverse slope of the spectrum T 0 for approximation Edcr/dp= Sehr(- T^/Tq) cross sections for the production of cumulative pions measured at an angle of 180. This means that the independence of the shape of the spectra from the primary energy begins with the difference in the speeds of the colliding particles \Yau-YAl\ > 2.

Another established pattern is the independence of the spectra of cumulative particles from the type of particle on which fragmentation occurs (see Fig. 2).

Since the dissertation paper considers experimental data on the fragmentation of polarized deuterons into cumulative pions, the regularities established in reactions with the production of cumulative particles (dependence on the atomic mass of the fragmenting nucleus, dependence on the type of detected particle, etc.) will not be discussed in more detail. If necessary, they can be found in the reviews: , , , .

- h

h 40 ZO

M і-

present experiment

About 7G*1TG "I

+ -

Present experiment v Reference 6

Rice. 1: Dependence on the energy of the incident proton (TR) (a) the inverse slope parameter T 0 and (b) the ratio of the outputs tt~/tg + , integrated starting from a pion energy of 100 MeV. Figure and data marked with circles are taken from . Data marked with triangles are cited from .

B.3 Description of polarized states of particles with spin 1

For the convenience of further presentation, we give a brief overview of the concepts , , which are used in describing the reactions of particles with spin 1.

Under ordinary experimental conditions, an ensemble of spin particles (beam or target) is described by the density matrix R, whose main properties are as follows:

Normalization Sp(jo) = 1.

hermiticity p = p + .

D-H"

.,- Withf

O - Si 4 -Pbsh l

, . f,

" -" -. і.. -|-і-

Cumulative Scale Variable Xwith

Rice. 2: Dependence of the cross section for the production of cumulative particles on the cumulative scaling variable Xwith (57) (see paragraph III.2) for the fragmentation of a deuteron beam on various targets into pions at zero angle. Picture taken from work.

3. Average from the operator About calculated as (O) = Sp(Op).

The polarization of an ensemble (for definiteness, a beam) of particles with spin 1/2 is characterized by the direction and average value of the spin. As regards particles with spin 1, one should distinguish between vector and tensor polarizations. The term "tensor polarization" means that the description of particles with spin 1 uses a tensor of the second rank. In general, particles with spin / are described by the rank tensor 21, so that for / > 1 one should distinguish between the polarization parameters of the 2nd and 3rd ranks, and so on.

In 1970, at the 3rd International Symposium on Polarization Phenomena, the so-called Madison Convention was adopted, which, in particular, regulates the notation and terminology for polarization experiments. When recording a nuclear reaction L(a, b)B Arrows are placed over particles that react in a polarized state or whose polarization state is observed. For example, the notation 3 H(rf,n) 4 He means that the unpolarized target 3 H is bombarded by polarized deuterons d and that polarization of the resulting neutrons is observed.

When talking about measuring the polarization of a particle b in a nuclear reaction, we mean the process L(a, b) B, those. in this case, the beam and the target are not polarized. The parameters describing the changes in the reaction cross section when either the beam or the target (but not both) are polarized are called the analyzing powers of the reaction of the form A(a, b)B. Thus, apart from special cases, polarizations and analytical abilities must be clearly distinguished, since they characterize different reactions.

Type reactions A(a, b)B, A(a, b)B etc. are called polarization transfer reactions. Parameters relating the spin moments of a particle b and particles a, are called polarization transfer coefficients.

The term "spin correlations" is applied to experiments on the study of reactions of the form A(a, b)B and A(a, b)B, moreover, in the latter case, the polarization of both resulting particles must be measured in the same event.

In experiments with a beam of polarized particles (measurements of analyzing abilities), in accordance with the Madison Convention, the axis z guided by the momentum of the beam particle kjn, axis y - on to(P X kout(i.e. perpendicular to the reaction plane), and the axis X must be directed so that the resulting coordinate system is right-handed.

Polarization state of a system of particles with spin I can be fully described by (2/+1) 2 -1 parameters. Thus, for particles with spin 1/2, three parameters pi form a vector R, called the polarization vector. Expression in terms of the spin 1/2 operator, denoted a, following:

Pi =yy,Z, (5)

where angle brackets mean averaging over all particles of the ensemble (in our case, the beam). Absolute value R limited \p\ 1. If we incoherently mix n + particles in a pure spin state, i.e. completely polarized in some given direction, and n_ particles completely polarized in the opposite direction, the polarization will be p =" + ^~ , or

+ p = N + ~N_, (6)

if under N + = PP+ P _ and JV_ = ~jf^- understand the fraction of particles in each of the two states.

Since the polarization of particles with spin 1 is described by a tensor, its representation becomes more complicated and less visual. Polarization parameters are some observable quantities

spin operator 1, S. Two different sets of definitions for the corresponding polarization parameters are used - Cartesian tensor moments ri rc and spin tensors tjsq. In Cartesian coordinates, according to the Madison Convention, the polarization parameters are defined as

Pi= (Si)(vector polarization), (7)

pij- -?(SiSj.+ SjSi)- 25ij(tensor polarization), (8)

where S- spin operator 1, i, j= x,y,z. Insofar as

S(S+1).= 2 , (9)

we have a connection

Рхх + Ruy + Pzz = 0 (10)

Thus, the tensor polarization is described by five independent quantities (pzx, Ruu, Rhu, pXz, Pyz)-> which, together with the three components of the polarization vector, gives eight parameters for describing the polarized state of a particle with spin 1. The corresponding density matrix can be written as:

P = \i^ + \is + \vij(SiSj+ SjSi)).. (11)

The description of the polarization state in terms of spin tensors is convenient, since they are easier than Cartesian ones, they are transformed during rotations of the coordinate system. The spin tensors are related to each other by the following relationship (see):

hq~ N(fc i9i fc 2&|fcg)4 w ,4 2(ft , (12)

where (kiqik 2 q2\kq) ~ Clebsch-Gordan coefficients, and N- normalization coefficient, chosen so that the condition is fulfilled

Sp.(MU) = (^ + 1)^,^ (13)

The lowest spin moments are:

І 11 \u003d 7 ^ (^ + ^ y) "(14)

t\ -\ = -^(Sx- iSy) .

For spin/index to runs values ​​from 0 to 21, a |e| j. Negative values q can be discarded because there is a connection tk _ q = (-1)41 + $# spin 1 spherical tensor moments are defined as

t\\ ~ ~*-(Sx ) (vector polarization),

tii.= -&((Ss+ iSy)Sg.+Sx(Sx+ iSy)) ,

hi = 2 ((Sx+ iSy) 2 ) (tensor polarization).

Thus, vector polarization is described by three parameters: real t\o and comprehensive "tu, and tensor polarization - five: real I20 and complex I2b ^22-

Next, consider the situation when the spin system has axial symmetry with respect to the С axis (notation z leave for the coordinate system associated with the reaction under consideration, as described above). This particular case is interesting because beams from sources of polarized ions usually have axial symmetry. Let us imagine such a state as an incoherent mixture containing a fraction N+ particles with spins along, fraction N- particles with spins along - and the fraction JVo of particles with spins uniformly distributed in directions in the plane perpendicular to k. In this case, only two polarization moments of the beam are nonzero, t to (or sch) and t 2 Q(or R#). Let us direct the quantization axis along the symmetry axis C and replace i in notation with t and z to (". It is obvious that (*%) is simply equal to N + - iV_, and according to (15) and (7):

tyu = \-(iV+-JV_) or (17)

p = (N + - i\L) (vector polarization).

From (16) and (8) it follows that

T2o = -^(l-3iVo) or (18)

Ptf= (1 - 3iVo) (tensor polarization or alignment),

where it is used that (JV+ + i\L) = (1 - iV 0).

If all moments of the 2nd rank are absent (N 0 = 1/3) speak of a purely vector beam polarization. The maximum possible values ​​of the polarization of such a beam

tії" = yfifi or C 19)

pmax. _ 2/3 (pure vector polarization).

For the case of purely tensor polarization (tu = 0) from equations (17) and (18) we obtain

-y/2 2 oily (20)

The lower bound corresponds No= 1, top - N+ ~ N_= 1/2.

In general, the axis of symmetry WITH, polarized beam from the source can be arbitrarily oriented with respect to the coordinate system xyz, associated with the reaction in question. Let us express the spin moments in this system. If the axis orientation ( set by angles /3 (between the axes z and C) and f(rotation on - f around the axis z brings the C-axis into a plane yz), as shown in Fig. 3, and in the system WITH, beam polarizations are t\ 0 , m 20 , then the tensor moments in the system xyz are equal:

Vector moments: Tensor moments:

t 20 = y(3cos 2 /?- i) , (21)

itn = ^8 IP0ЄIf. til= " %T2 % Silljgcos/fe**",

y/2 y/2

In the general case, the invariant section a = Edijdp reactions A(a,b)B is written as:

Quantities T)sch are called the analyzing abilities of the reaction. The Madison Convention recommends that tensor analyzing powers be denoted as Tkq (spherical) and AitAts(Cartesian). Four analyzing abilities - vector GTand and tensor T 20 , TG\ and Тії

Rice. 3: Orientation of the axis of symmetry ( polarized beam relative to the coordinate system xyz, associated with the reaction xz- reaction plane, /3 - angle between the axes z(direction of the incident beam) and, rotation on - f around the axis z leads axle; into the plane yz.

- are real due to parity conservation, and 7\ 0 = 0. Taking into account these restrictions, equation (22) takes the form:

a = cro, , , . On the whole, the experimental spectra obtained are well described by the spectra

tator mechanism using conventional WFD, for example, the Reid or Paris WFD.

Rice. 5: Nucleon relative momentum distribution in the deuteron extracted from experimental data for various reactions involving the deuteron. Picture taken from work.

So, from Fig. 5 shows that the momentum distributions of nucleons in the deuteron are in good agreement, extracted from the data for the reactions: inelastic scattering of electrons on the deuteron d(e,e")X, elastic proton-deuteron backward scattering p(d,p)d, and the collapse of the deuteron. Except for internal pulse interval to from 300 to 500 MeV/c, the data are described by the spectator mechanism using the Paris PFD. Additional mechanisms have been invoked to explain the discrepancy in this area. In particular, taking into account the contribution from pion rescattering in the intermediate state , , makes it possible to satisfactorily describe the data. However, the uncertainty in the calculations is about 50 % due to uncertainty in the knowledge of the vertex function irn, which, in addition, in such calculations must be known outside the mass shell. In this work, to explain the experimental spectra, we took into account the fact that for large internal momenta (i.e., small internucleon distances)

yany Inn- 0,2/"to) non-nuclear degrees of freedom may appear. In particular, in that work, an admixture of the six-quark component \6q), the probability of which was ~-4.%.

Thus, it can be noted that, on the whole, the spectra of protons obtained during the fragmentation of deuterons into protons at zero angle can be described up to internal momenta of ~ 900 MeV/c. In this case, it is necessary either to take into account the diagrams following after the momentum approximation, or to modify the PFD taking into account the possible manifestation of nonnucleon degrees of freedom.

The polarization observables for the deuteron breakup reaction are sensitive to the relative contribution of the PFD components corresponding to different angular momenta, so experiments with polarized deuterons provide additional information about the deuteron structure and reaction mechanisms. At present, there are extensive experimental data on the tensor analyzing power T 2 about for the breakup reaction of tensor polarized deuterons. The corresponding expression in the spectator mechanism is given above, see (30). Experimental data for T 2 q, obtained in works , , , , , , , , , are shown in Figs. 6, which shows that starting from internal momenta of the order of 0.2 × 0.25 GeV/c, the data are not described by generally accepted two-component PFDs.

Accounting for interaction in the final state improves agreement with experimental data up to momenta of the order of 0.3 GeV/c. Accounting for the contribution of the six-quark component in the deuteron allows one to describe the data up to internal momenta of the order of 0.7 GeV/c. Behavior T 2 about for momenta of the order of 0.9 - L 1 GeV/c is in best agreement with calculations in the framework of QCD using the method of reduced nuclear amplitudes, , taking into account the antisymmetrization of quarks from different nucleons.

So, summing up the above:

Experimental data for the fragmentation cross section of unpolarized deuterons into protons at zero angle can be described in terms of the nucleon model.

Up to now, the data for T20 have been described only in terms of non-nucleon degrees of freedom.

Methodical measurements and modeling

Measurements of the tensor analyzing capacity G20 of the reaction d + A -(0 - 0) + X fragmentation of relativistic polarized deuterons into cumulative pions were carried out on channel 4V of the slow extraction system of the Synchrophasotron LHE JINR. Channel 4B is located in the main measuring hall of the accelerator complex (the so-called building 205). Polarized deuterons were created by the POLYA-RIS source, which is described in .

The measurements were carried out under the following conditions: 1. the stretching value (extraction time) of the beam was 400 500 ms; 2. repetition rate 0.1 Hz; 3. the intensity varied in the range from 1109 to 5109 deuterons per drop; 4. The value of the tensor polarization of the deuteron beam was pzz 0.60-0.77, varying slightly (by no more than 10%, see .25; 5: the quantization axis for polarization was always directed vertically; 6. Three polarization states were provided - "+" (positive sign of polarization), "-" (negative sign of polarization), "0" (absence of polarization), which changed every accelerator cycle, so that in three successive cycles the beam had different polarization states. In the first series of measurements, carried out in March 1995, the magnitude of the vector and tensor polarization was measured at the beginning and end of the full cycle (session) of measurements using a high-energy polarimeter described in the work - the so-called. polarimeter ALPHA.

In the first series of measurements , , , we used the one shown in Fig. 8 is the configuration of the setup with the target located at the focus F3 (we will call it the “first setup” for brevity).

The extracted beam of primary deuterons was focused by a doublet of quadrupole lenses onto a target located at focus F3. The intensity distribution on the target in the plane perpendicular to the beam direction was close to the Gaussian distribution with dispersions mx n 6 mm and y ≈ 9 mm along the horizontal and vertical axes, respectively. Cylindrical carbon targets (50.4 g/cm2 and 23.5 g/cm2) with a diameter of 10 cm were used, which made it possible to assume that the entire primary beam hit the target.

Monitoring of the intensity of the deuteron beam incident on the target was carried out using the ionization chamber 1C (see Fig. 8), located in front of the target at a distance of 1 m from it, and two scintillation telescopes Mi and M2, three counters each, aimed at an aluminum foil 1 mm thick. Monitors have not been completely calibrated. The difference in determining the relative intensity on different monitors reached 5%. This difference was included in the systematic error.

Scintillation counters at foci F4 (F4b F42), F5 (F5i) and F6 (F6i) were used to measure the time of flight at bases of 74 meters (F4-F6) and 42 meters (F5-F6). Scintillation counters Si and Sz, and, if necessary, a Cherenkov counter C (with a refractive index n = 1.033) were used to generate the trigger. Scintillation hodoscopes HOX, HOY, HOU, H0V were used to control the beam profile in F6. The characteristics of the counters are given in Table 1. The first setting of the experiment, due to the presence of six deflecting magnets, made it possible to have a negligibly small (less than 10–4) background/signal ratio for time-of-flight spectra even on positively charged particles. The suppression of protons (by two orders of magnitude) in the trigger using a Cherenkov counter was used to reduce the dead time. The inconvenience of such a setting is associated with the need to reconfigure a large number of magnetic elements. Therefore, experimental data in the first setting were collected at a fixed pion momentum of 4 V (3.0 GeV/c), the increase in the subthreshold degree of which was achieved by reducing the deuteron momentum. In the second series of measurements, carried out in June-July 1997, data were collected in a slightly different configuration of the setup with the target located at the F5 focus (hereinafter referred to as the "second setup"), as shown in Fig. 9. In such a formulation, the loads of head counters increase, especially in measurements on positive particles. To reduce the influence of such loadings, an NT scintillation hodoscope was used in the head part, which consisted of eight plastic scintillators viewed from both sides of the FEU-87. Signals from this hodoscope were used for time-of-flight analysis (based on 30 m), which in this case was carried out for each element independently. The position and profile of the beam (ax 4 mm, ty = 9 mm) on the target were monitored by a wire chamber, the intensity - by a 1C ionization chamber and M and Mg scintillation telescopes. The measurements of the second series were carried out with a hydrogen target (7 g/cm2), a beryllium target (36 g/cm2) in the form of a parallelepiped with a minimum transverse (relative to the beam) size of 8x8 cm2 and a carbon target (55 g/cm2) of a cylindrical shape with a diameter of 10 cm. are shown in table 3.

Configurable data and hardware views

The recommended way to write a working module is that reads and writes are performed as buffered input and output operations on the standard input and output streams of a blocking process; the SIGPIPE signal and the EOF state cause the process to terminate normally. The working module can be implemented both dependent and independent of the composition of the collected data (i.e., the content of the packet bodies) and the serviced equipment (hereinafter referred to as "session-dependent" and "session-independent"4, respectively).

The control module is a process that does not work with a stream of data packets and is intended, as a rule, to control some element (s) of the qdpb system. The implementation of such a module, therefore, does not depend on the contents of the packet stream, nor on the contents of the packet bodies, which ensures its universality (session independence).

In addition, processes that receive source data not through packet flows are also classified here, for example, modules for representing (visualizing) processed data in the current implementation of the SPHERE DAQ system, see paragraph II.5. Such a control module may be implemented in either a session-independent or a session-dependent manner.

A service module is a process that organizes packet flows and does not make changes to them. It can read from the packet stream and/or write to the packet stream, while the contents of the input and output streams of the service module are identical. The implementation of the service module does not depend on the contents of the packet stream, nor on the contents of the packet bodies, which ensures its universality.

A branch point is a start and/or end point for multiple packet streams and is intended to create multiple identical output packet streams from several different input packet streams (generated by different sources). The branch point does not change the content of the packages. The implementation of the branch point is independent of the contents of the packet streams, which makes it universal. The order of the packets from the various input streams in the output stream is arbitrary, but the order of the packets of each of the input streams is preserved: The branch point also implements a packet buffer and provides a means of managing it. It is recommended to implement a branch point as part of the OS kernel (in the form of a loadable module or driver) that provides the appropriate system call (calls) for managing its own state, issuing this state outside, managing the packet buffer, registering input and output streams working with it. Depending on the internal state, the branch point syscall receives (blocks receiving, receives and ignores) packets from any input stream and syscall sends (blocks sending) all(x) received packet(s) to output streams.

The event stitcher5 is a variant of the branch point, also designed to create several identical output packets from several different (from different sources) input streams of packets. The event stitcher modifies the content of the packets in the following way: the header of each of the output packets is obtained by making a new packet header, and the body is obtained by sequentially connecting the bodies of one or more (one from each registered input stream - the so-called input channel) so-called. input packets "corresponding" to it. In the current implementation, in order to match input and output packets, the following is required: - match of types (header.type) of input and output packets declared for each input channel when it is registered, and - match of numbers (header.num) of input packets for candidates for matching in all input channels. The term "event stitcher" was introduced because it more accurately characterizes the proposed (rather simple) functionality, in contrast to rather complex systems called "event builder". Packets with types that do not have a declared match are discarded when they enter the input channels. Packets with numbers that do not match in all input channels are discarded. The implementation of the event stitcher is independent of the contents of the packets. It is recommended to implement the event stitcher as part of the OS kernel (in the form of a loadable module or driver) that provides the appropriate system call (calls) for managing its own state, issuing this state outside, and registering input and output streams working with it. The supervisor is a control (or working, if control packages are implemented) module that at least starts, stops and controls the qdpb system at the command of the system user (hereinafter referred to as the "operator"). The correspondence of the supervisor's actions to the operator's commands is described in the configuration file of the first sv.conf(S). In the current implementation, the configuration file is a makefile. The elements of the qdpb system are managed through the mechanisms provided by those elements. The managed elements of the qdpb system are: elements of the OS kernel (loadable modules of the hardware maintenance subsystem, branch point(s), event stitcher(s); working modules. Management of other elements of the qdpb system is not provided, as well as the reaction to situations in the system. For remote control, i.e. managing elements of the qdpb system on computers other than the supervisor executing the process (hereinafter referred to as "remote computers"), the supervisor launches control modules on them using standard OS tools - rsh(l) / ssh(l), rcmd(3) win rpc(3 ). For the operator's dialogue with the supervisor, the latter can implement an interactive graphical user interface (Graphics User Interface, hereinafter referred to as "GUI") or an interactive command line interface. Some elements of the qdpb system that have their own GUI can be controlled directly by the operator, without the participation of a supervisor (for example, data presentation modules). The above project was largely implemented. Let's consider in more detail the key points of implementation.

Polarimeter Data Acquisition Systems

By default, the sphereconf utility configures the specified loadable module module to work with the "kkO" CAMAC hardware driver. No specific information is passed to the loadable module. When specified on the command line, the sphereconf utility tests the configuration of the specified module load module and prints it to the error output stream. The default behavior of the sphereconf utility is changed by the above command line switches. The sphereconf utility returns code zero on success and positive otherwise. The sphereoper(8) control utility for the CAMAC interrupt handler is called sphereoper and has the following command interface: sphereoper [-v] [-b # ] startstop)statusinitfinishqueclJcntcl line, in the loadable module attached to the 0th branch of CAMAC, and outputs the execution result to the error output stream. Thus, the sphereoper utility can be used to implement some of the actions described in the supervisor's sv.conf(5) configuration file. The default behavior of the sphereoper utility is changed by the above command line switches. The sphereoper utility returns code zero on success and positive otherwise. To measure the speed of execution of CAMAC commands, a custom CAMAC speedtest interrupt handler was also implemented (for more details on testing the DAQ SPHERE system on the bench, see below), which, for each processed interrupt from CAMAC, executes the configured number of times the tested CAMAC command (selected by changing the source file speedtest.c ). The speedtest load module is configured by the stconf(8) utility and controlled by the sphereoper(8) utility (only the start, stop, status, and cntcl values ​​of the first positional argument are supported).

Compared to the sphereconf (8) utility, the stconf(8) configuration utility has an additional optional command line switch -p # for passing specific information to the loadable module, which means the number of repetitions of the tested CAMAC command, which is 10 by default, otherwise similar to the last one.

The SPHERE DAQ system uses (in a non-distributed, i.e., executable entirely on one computer, configuration) at least the working module writer(1), the service module bpget(l) and (optionally) control modules - the supervisor sv(l) and the module a graphical representation of the alarm(1) system log from the session-independent set of plug-ins provided by the qdpb system. Next, consider the software modules specific to the DAQ SPHERE system.

The statistics collector in the current implementation is called statman and is, in terms of the qdpb system, a working module, a packet stream consumer that accumulates data in shared memory in a form convenient for use by data presentation software modules (see below), and has the following command interface: statman [- o] [-b bpemstat [-e] ] [-c(- runcffile )]. [-s(- cellcffile )J [-k(- knobjcffile )] [-i(- cleancffile )] [-p(- pidfile )]

By default, the statman module reads packets from the standard input stream, collects information from the packet.data body of each incoming packet, and accumulates it in shared memory in accordance with the default configuration files. On startup, the statistics collector reads configuration files in the RVN.conf(5), cell.conf(5), knobj.conf(5) and clean.conf(5) formats (see paragraph P.3) and accordingly initializes the internal arrays of structures pdat, cell, knvar, knfun, knobj; runs a creation cycle over all initialized known objects and generates the PR0G_BEG event, after which it reads packets from the standard input stream and for each received packet increases the global counter corresponding to its type of event and performs a cycle of calculating the results for all initialized cells and a filling/clearing cycle for all initialized known objects. Upon receiving an EOF end-of-file condition on standard input or a SIGTERM signal, it generates a PR0G_END event, so a SIGKILL abort is not recommended. The PR0G_BEGIN and PR0G_END events are also used to calculate the results for all initialized cells and the fill/clear cycle for all initialized known objects.

The default behavior of the statman module is changed by the above command line switches.

The statman module returns code zero on success and positive otherwise.

The statman module ignores the SIGQUIT signal. The SIGHUP signal is used to reconfigure an already running statman module by rereading the configuration files runcffile , cellcffile and knobjcffile (but with the same names as when the module was started), which leads to a complete clearing of all information accumulated at the moment and resetting the results of all computations. cells, i.e. completely equivalent to configuring at startup. The SIGINT signal results in a new reading of the cellcf file configuration file (with the same name as at startup) without resetting the cell results, which can be used to "reprogram" them on the fly. The SIGUSR1 signal clears all accumulated information, including internal global event counters, the SIGUSR2 signal clears accumulated information according to the configuration file cleancffile . Both of these signals also reset the results of all calculation cells. The SIGTERM signal must be used to send a request for a graceful termination to the module.

The configuration file of known objects of the statman module can only contain declarations of types supported by the module, currently the following: "hist", "hist2", "cnt", "coord" and "coord2" (see section II.3 for details). For each line of data in such a file, the first (name), third (type), fifth (fill event), sixth (fill condition), and seventh (fill event) fields have their standard knobj.conf(5) format value. The fields representing the arguments of the create (second), fill (fourth), clear (eighth), and destroy (ninth) functions must conform to the API of the respective families of known functions.

Analysis of sources of systematic errors

The textual data representation module is intended for textual visualization of information accumulated in shared memory by the statistics collector, it is called cntview and has the following command interface: cntview [-k(-I knobjconffile )] [-p(- pidfile )] [ sleeptime.

By default, the cntview module reads the data accumulated in shared memory by the statistics collector statman(l), interprets it according to the default configuration file in the knobj.conf(5) format, and prints its text (ASCII) representation to the error output stream.

The default behavior of the cntview module is changed by the above command line switches. The cntview module returns code zero on success and positive otherwise. The cntview module ignores the SIGQUIT signal. The SIGHUP signal is used to reconfigure an already running cntview module by rereading the configuration file (but with the same name as when the module was started). The SIGUSR1 signal suspends and the SIGUSR2 signal resumes reading information from shared memory and displaying it. The SIGINT signal redirects the next data output to the printer with the compiled name via the Ipr(1) utility. The SIGTERM signal must be used to send a request for a normal termination to a module. The cntview module's known object configuration file can only contain declarations of the "dent" type supported by the module (see Section II.3 for details). For the known object "dent", the first (name), third (type), fifth (fill event), sixth (fill condition) and seventh (fill event) fields of the data string have their standard value for the knobj.conf(S) format, then as the fields representing the arguments of the create (second), fill (fourth), clear (eighth) and destroy (ninth) functions, must conform to the API of the corresponding family of known functions. For example, the declaration of one known object of type "dent" is written as follows: Obj0041 41;shmid;semid dent 41;3;semid;type_ULong;nht,type_String;4;cnt21:cnt22:cnt23 \ DATA_DAT_0 - NEVERMORE gen prescfg(l) utility (see paragraph II.3) generates the declaration of the known object "dent" above from the prototype of the following form: dent 41 1 -1 shmid semid 3 ULong nht 4 cnt%2lN DAT_0 - N The OS kernel load module control utility is called watcher and has the following command interface: watcher [-b # ] [-p(- pidfile )] [ sleeptime ] By default, the watcher utility collects status information at intervals of 60 seconds (by calling oper() with the HANDGETSTAT subfunction) from the KA user interrupt handler -MAK, attached to the 0th branch of CAMAC, analyzes the state of the latter, taking into account previously received similar information, and issues error messages to the error output stream. Thus, the watcher utility can be used in conjunction with the alarm(1) syslog graphical module to report certain errors in the SPHERE DAQ system. The default behavior of the watcher utility is changed by the above command line switches. The watcher utility returns code zero on success and positive otherwise. The watcher utility ignores the SIGHUP, SIGINT, and SIGQUTT signals. The SIGUSR1 signal suspends and the SIGUSR2 signal resumes information collection. The SIGTERM signal must be used to send a request for a graceful termination to the module. The supervisor sv(l) described in paragraph II.2 can be used to control the SPHERE DAQ system. It is also possible to directly, without the help of the supervisor, execute the make (1) utility with the same names to the commands of the target operator (target) from the configuration file of the supervisor sv.conf. Let's describe the purpose of the operator's main commands: load - loading and configuring loadable modules of the OS kernel - branchpoint (4) and the custom CAMAC sphere (4) interrupt handler, launching the bpget(l) service module and attaching it (in the BPRUN state) to the branchpoint , initialization of CAMAC equipment. unload (reverse to load command) - deinitialization of the CAMAC hardware, termination of the bpget(l) module, unloading of the branch point and CAMAC custom interrupt handler, loadw - launch of the working module writer (1) with a request to enter the necessary parameters and a reminder of the possibility of entering optional ones and attaching it (in the BPSTOP state) to the branch point. unloadw (reverse to loadw command) - end of the writer module (1). loads - Runs a statman(l) worker and attaches it (in BPSTOP state) to a branch point. unloads (reverse to loads command) - completion of the statman (1) module. loadh - launches the histview (1) graphical data representation module using the xterm(l) utility in a separate window of the XII graphic system. unloadh (reverse to loadh command) - end histview module (1). loadc - launches the cntview (1) text representation module using the xterm(l) utility in a separate window of the XII graphic system. unloadc (inverse to loadc command) - end of the cntview (1) module. start_all - Change the state of all attachments to the branch point to BPRUN. stop_all (reverse to start_all command) - change the state of all attachments to the branch point to BPSTOP. init - initialization of the CAMAC equipment (it is necessary to execute it, for example, after turning on the power supply of the crates being read, it is also included in the load). finish (reverse to init command) - deinitialization of CAMAC equipment (should be performed, for example, before turning off the power, also included in unload). continue - start processing CAMAC interrupts and start the watcher utility. pause (reverse to continue command) - the end of the watcher utility and the termination of CAMAC interrupt processing. cleanall - cleanup of all information accumulated in shared memory by the statman module (1). clean - cleanup of information accumulated in shared memory by the statman (1) module, in accordance with the configuration file specified when the module was launched in the clean.conf(5) format. pauseh (reverse to conth command) - pause the rendering of data by the histview module (1). pausec (inverse to contc command) - suspending data rendering by the cntview (1) module. conth - continuation of data visualization by the histview module (1). contc - continuation of data visualization by the cntview module (1). status - outputs a summary of the status of the loaded elements of the DAQ SPHERE system to the log files of the syslogd(8) daemon. seelog - start viewing messages from the DAQ SPHERE system entering the log files of the syslogd(8) daemon using the tail(l) utility. confs - pause data visualization by histview (1) and cntview (1) modules, reconfigure statman (1), histview (1) and cntview (1) modules, continue data visualization (used after changing the corresponding configuration files). The DAQ SPHERE system currently uses the following freely distributed third-party software packages (in addition to those "inherited" from the qdpb system): satas package - implementation of the CAMAC service subsystem. ROOT package - used as a histogram graphical visualization API to implement the histview (1) data view module.

Golyshkov, Vladimir Alekseevich

A deuteron is a nucleus consisting of one proton and one neutron. By studying the properties of this simplest nuclear system (deuteron binding energy, spin, magnetic and quadrupole moments), one can choose a potential that describes the properties of the nucleon-nucleon interaction.

The deuteron wave function ψ(r) has the form

is a good approximation for the entire range of r.
Since the spin and parity of the deuteron are 1 + , the nucleons can be in the s-state (L = 0 + 0), and their spins must be parallel. The absence of a bound state with spin 0 in the deuteron says that the nuclear forces depend on the spin.
The magnetic moment of the deuteron in the S-state (see Magnetic moment of the nucleus) μ(S) = 0.8796μ N , is close to the experimental value. The difference can be explained by a small admixture of the D state (L = 1 + 1) in the deuteron wave function. Magnetic moment in the D-state
μ(D) = 0.1204μ N . The D-state impurity is 0.03.

The presence of an admixture of the D-state and a quadrupole moment in the deuteron testify to the non-central character of nuclear forces. Such forces are called tensor forces. They depend on the magnitude of the projections of spins s 1 and s 2 , nucleons on the direction of the unit vector , directed from one deuteron nucleon to another. The positive quadrupole moment of the deuteron (prolonged ellipsoid) corresponds to the attraction of nucleons, the flattened ellipsoid corresponds to repulsion.

The spin-orbit interaction manifests itself in the features of the scattering of particles with nonzero spin on non-polarized and polarized targets and in the scattering of polarized particles. The dependence of nuclear interactions on how the orbital and spin moments of the nucleon are directed relative to each other can be found in the following experiment. A beam of unpolarized protons (spins with the same probability are directed conventionally "up" (blue circles in Fig. 3) and "down" (red circles)) falls on the 4 He target. Spin 4 He J = 0. Since the nuclear forces depend on the relative orientation of the vectors of the orbital momentum and spin , protons are polarized during scattering, i.e. protons with spin "up" (blue circles), for which ls, are more likely to scatter to the left, and protons with "down" spin (red circles), for which ls, are more likely to scatter to the right. The number of protons scattered to the right and to the left is the same, however, upon scattering at the first target, beam polarization occurs - the predominance of particles with a certain spin direction in the beam. Further, the right beam, in which protons with spin "down" predominate, falls on the second target (4 He). Just as in the first scattering, protons with spin "up" mostly scatter to the left, and those with spin "down" mostly scatter to the right. But since in the secondary beam, protons with spin "down" predominate; upon scattering on the second target, the angular asymmetry of the scattered protons relative to the direction of the beam incident on the second target will be observed. The number of protons that are registered by the left detector will be less than the number of protons that are registered by the right detector.
The exchange nature of the nucleon-nucleon interaction manifests itself in the scattering of high-energy neutrons (several hundreds of MeV) by protons. The differential neutron scattering cross section has a maximum for backscattering in the cm, which is explained by the charge exchange between a proton and a neutron.

Properties of nuclear forces

1. Short range of nuclear forces (a ~ 1 fm).
2. Large value of the nuclear potential V ~ 50 MeV.
3. Dependence of nuclear forces on spins of interacting particles.
4. Tensor character of interaction of nucleons.
5. Nuclear forces depend on the mutual orientation of the spin and orbital moments of the nucleon (spin-orbit forces).
6. Nuclear interaction has the property of saturation.
7. Charge independence of nuclear forces.
8. Exchange character of nuclear interaction.
9. Attraction between nucleons at large distances (r > 1 fm) is replaced by repulsion at short distances (r< 0.5 Фм).

The nucleon-nucleon potential has the form (without exchange terms)