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The results of the study of dp-elastic scattering at the energies from 500 to 1000 MeV/nucleon

A.A Terekhin et al.

Joint Institute for Nuclear Research, Dubna, Russia

HS’2015

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Introduction The purpose of DSS (Deuteron spin structure) project is the

broadening of the energy and angular ranges of measurement of

different observables in processes including 3-nucleon systems. The

study of the dp-elastic scattering at various energies in large angle

range is one of directions in this domain.

The experimental setup at internal target station (ITS) at

Nuclotron allows us to obtain the different observables at angle range

60-140o in the c.m.s. We shown in this presentation preliminary data of

differential cross section for dp-elastic scattering at 500,

650,700,750,900 and 1000 Mev/n, obtained at ITS Nuclotron.

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Energe, MeV/n Engle range in c.m.s. Cite

425 27.87 - 180 Booth,1971

470 91 - 163 Alder,1972

580 30 - 180 Vincent,1970

582 16.9 – 166.2 Boschitz,1972

590 92.7 – 163.8 Alder,1972

594 60 - 150 Albrow,1971

641.3 34.89 – 115.22 Culmez,1991

792.7 34.43 – 139.78 Culmez,1991

796 (dsigma/dt) 7.97 – 22.80 Irom,1983

800 14.1 – 153.5 Winkelmann,1980

1000 10-180 Bennett, 1967

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Measurements on the Internal target station

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Layout of the counters with respect to the beam direction

P = 20x60x20 mm3

D = 10x40x24 mm3

PP = 50x50x20 mm3

P = 20x60x20 mm3

D = 50x50x20 mm3

PP = 100х200 mm3

500-900 MeV/n 1000 MeV/n

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VME Data Acquisition System

TQDC-16 – 16 - channel time and charge digitizer

TQDC-16TTCM GUI Controls

The VME based data acquisition system was used for the data taking from scintillation detectors.

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The estimation of the background in the amplitude data was performed by using the temporary gates on the deuteron and proton time difference spectra. The subtraction of the timing signal from deuteron-and proton-counters was made by using the cut for signal amplitudes correlation In this distribution the dp-elastic scattering events (Idomain) and the background (II and III domains) are selected so that the width of both domains are equal.

A - The amplitude distribution for proton counter by using these timing gates. B - The subtraction of the resulting spectra allows reducing of the background

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CH2-C subtraction

The next stage is the CH2-C subtraction procedure. Carbon background subtraction deduced from the normalization in the interval amin<a<amax, were a - channels of CH2- and C-amplitude distributions. I.e.

maxmin

maxmin2

aaaC

aaaCH

|N

|Nk

were k - normalization coefficient, NCH2 and NC - CH2- and C-amplitude distributions integrals in a-interval. The carbon background can be subtracted as:

CCHdp kNNN2

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Differential cross section at 1000 MeV/n

Squares – new dataCircles – the data obtained early for forward angles [Terekhin A.A. et al. EPJ A48, 2012. P.182.]

Triangles - Bennett G. W. et al. Phys. Rev. Lett. 1976. V.19 P. 387-390.The dashed and solid lines are the calculations without and with DS term, respectively. [Ladygina N.B. et

al. EPJ A42, 2009. P.91.]

The dashed and solid lines are the calculations without and with DS term, respectively. One can see that the new data at c.m 90o are in good agreement with the world data. The discrepancy is increased at large angles, nevertheless, the data are in agreement with the errors which increase with the angle increasing. On the other hand, there is better agreement with theoretical calculations taking into account DS at these angles. This figure shows that the single scattering mechanism does not reproduce the experimental data at the scattering angles c.m larger than 45o. The inclusion of the double scattering term in the calculations provides better agreement with the experimental results.

The data for differential cross section are compared with the world data and with the theoretical predictions. The new data are shown by the solid squares [arXiv:1503.07968].The errors are the statistical only. The systematic errors are shown by the solid gray band. The data obtained earlier for forward angles are shown by the solid circles. The open triangles are world data obtained with a monochromatic protons beam at the Brookhaven Cosmotron by using a liquid-deuterium target.

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Triangles – data at 641.3 MeV/n (Culmez E. Phys.Rev.C, V43, №5, 1991)

Differential cross section

650 MeV/n

750 MeV/n

Blue triangles – data at 792.7 MeV/n (Culmez E. Phys.Rev.C, V43, №5, 1991)

Green triangles – data from 800 MeV/n (Winkelmann E. Phys.Rev.C, V21, №6, 1980)

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The detectors misalignment determinationThe determination of the detectors misalignment were performed to improve the accuracy of the experiment. The following measurements were performed at the 700 MeV/n for each angle scattering in the c.m.s. Since the angle span of the deuteron counter in the c.m.s. is wider than the angle span of the proton counter the deuteron counter is fixed at kinematical angle in the lab. sys. but the proton counter is moved around corresponded angle. For this case the relative yields was measured.

The angle span of the deuteron- and proton - counter

The dp-elastic scatterind events simulation

The experimental relative yields for proton detectors as a function

of detector angle for 70o in the c.m.s.

We performed the simulation of dp-elastic scatterind events by using the Pluto peckage. The statistics is reduced about two times if the shift of the detector egual 2o in the c.m.s. After this the measurements to obtained of the dp-elastic scatterind yields were performed. The yield is normalized by guasi-elastic scattering yield. Filled and open symbols correspond to yields for one and other proton detectors.

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Differential cross section

700 MeV/n

The angular dependence for differential cross section at 700 MeV/n

The data for 500 and 900 MeV/n are in the at the analysis stage

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Conclusion

The procedure on the dp-elastic scattering differential cross section at high energies at ITS at Nuclotron using CH2 - C subtraction is established.

The data obtained at 1000 MeV/n are compared with the calculations performed within the framework of the relativistic multiple scattering theory. It is shown that taking into account the double scattering term improves the description of the obtained experimental results.

The preliminary differential cross section data for dp-elastic scattering at 500,650,750 and 900 MeV/n are obtained. New results are compared with the existing data for similar values of energies.

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Thank you for attention!