Dmitri Toporkov Budker Institute of Nuclear Physics Novosibirsk, Russia SPIN2005, Dubna, Russia

Dmitri Toporkov, SPIN2005, Dubna

Measurement of Tensor Analyzing Power in Deuteron

Photodisintegration at the VEPP-3

Storage RingDmitri ToporkovDmitri Toporkov

Budker Institute of Nuclear Budker Institute of Nuclear PhysicsPhysics

Novosibirsk, RussiaNovosibirsk, Russia

SPIN2005, Dubna, RussiaSPIN2005, Dubna, Russia

October 1, 2005October 1, 2005


Outline

1. Physical motivation2. Experimental arrangement3. Polarized target4. Detector5. Results 6. Summary

Measurement of Tensor Analyzing Power in Deuteron Photodisintegration at the VEPP-3 Storage Ring


• Deuteron is an important laboratory to test physical theories, it is the simplest nuclear system for the study of the N N –interaction.

• Electromagnetic probes – elastic electron scattering, photo or electro

disintegration.• Measurement of the electromagnetic form factors of the

deuteron, contribution to the N N –interaction of meson exchange currents, isobar configuration, relativistic correction, final state interaction, retardation effects in the meson exchange current



Polarization observables

1. Deuteron photodisintegration has been a subject of extensive experimental and theoretical studies for a long time.

2. A lot of experimental data exist for the case when -beam is polarized or target is vector polarized.

3. However data on tensor polarization observables are still very limited. There are data only from two experiments prior to the present one and both experiments have been performed at BINP, Novosibirsk.



Novosibirsk Electron-Deuteron CollaborationL.M.Barkov, V.F.Dmitriev, M.V.Dyug, L.G.Isaeva,

A.V.Grigoriev,B.A.Lazarenko, S.I.Mishnev, D.M.Nikolenko, I.A.Rachek, R.Sh.Sadykov, Yu.V.Shestakov, D.K.Toporkov and S.A.Zevakov

BINP, Novosibirsk, RussiaA.Yu.Loginov, A.N.Osipov, A.A.Sidorov and V.N.Stibunov

INR, Tomsk, RussiaR.Gilman

Rutgers University, Piscataway, NJ, USAE.R.Kinney

Colorado University, Boulder, CO, USAR.J.Holt and D.H.Potterveld

ANL, Argonne, IL, USAC.W.de Jager1 and H. de Vries

NIKHEF, Amsterdam, The NetherlandsS.L.Belostotsky, V.V.Nelyubin and V.V.Vikhrov

INP, St.-Petersburg, RussiaH.Arenhovel

IKP, Johanness Gutenberg-Universitat, Mainz, Germany 1Present address: TJNAF,Newport News, VA, USA Measurement of Tensor Analyzing Power in Deuteron Photodisintegration at the VEPP-3 Storage Ring


VEPP-3Energy : 2000 MeVLifetime : 20000 sAv. current : 100 mABunch : 0.7x0.3 mm

Novosibirsk electron-positron facility




Definition of kinematic variables for the reaction ( d, pn) in the center of mass frame


Photodisintegration of polarized deuteron

Scattering angle is small, therefore q2 close to zero andphoton is almost real. Process is photodisintegration


ddd/d0 {1 + PZZ/√2[( 3 cos2 */2 +

-√3/8 sin 2*cos *T21 + √3/8 sin2*cos 2* T22]}



aT0 ~ c0T20

aT1 ~ c1T21 + c2T22

aT2 ~ -c1T21 + c2T22

T20 T22T21

ci depend on the geometry of the detector and target


Top view of the internal target at VEPP-3 electron ring



Cryogenic Atomic Beam Source

Liquid nitrogen

Tenzor polarizationVector polarization

CryostatCryostat

Turbopump



ABS just before the installation at the straight sectionABS just before the installation at the straight section

Magnetic pole tip field of superconductingsextupole magnet up to 4.8 T



Storage cell for polarized atoms

Beam flux of polarized deuterium atoms 8.2x1016 at/secThe measured target thickness 8x1013 at/cm2



The layout of the detector system, side view

A - tangstem convertorB - brass baseC - scintillation fibers

200x200x1000 mm

120x400x1000 mm



LQ polarimeter measure the asymmetry in elastic ed scattering at small momentum transfer - Q = 0.105 (GeV/C), = 9.3.

○22

At small momentum transfersT ≈ -√2/3 Q QQ = 0.2859 fm - deuteron static quadrupole moment

20

D

2D

2

e

At Q = 0.105 (GeV/C) all 'reasonable' theoretical predictions for T coincide within ±5% range

2 2

20

LQ polarimeter


If analyzing powers are known the polarization of the target can be determined through the asymmetry


The average degree of targetpolarization during the run was found to be PZZ = 0.318 _ 0.019

LQP


+


τ =8000sectarget

τ =20000secnotarget

Charge accumulation during one shift of the experiment



Charge accumulation during the experiment



Proton: F, E/E Neutron: F, charge veto

Kinematic correlations:p-n energyp-n polar angle

p-n azimuthal angle Measurement of Tensor Analyzing Power in Deuteron Photodisintegration at the VEPP-3 Storage Ring

Background protonsfrom reactiond(e,pp)-e’


Preliminary results on T20, T21 and T22 vs. E for different

K.-H.Schmitt and H. Arenhovel, Few-Body Syst. 7(1989)95 M.I.Levchuk, Few-Body Syst. 19(1995)77

cmp



K.-H.Schmitt and H. Arenhovel, Few-Body Syst. 7(1989)95 Yu.P.Melnik and A.V.Shebeko, PRC 48(1993)23 =1.2Gev ibid =4m

M.I.Levchuk, Few-Body Syst. 19(1995)77

Preliminary results on T20 with = 83-93 (full circles) and old data Phys.Lett. B302 (1993) 277 (open circles)

cmp



K.-H.Schmitt and H. Arenhovel, Few-Body Syst. 7(1989)95 Yu.P.Melnik and A.V.Shebeko, PRC 48(1993)23 =1.2Gev ibid =4m

M.I.Levchuk, Few-Body Syst. 19(1995)77

Preliminary results on T22 with = 83-93 (full circles) and old data Phys.Lett. B302 (1993) 277 (open circles)

cmp



Preliminary results on T20, T21 and T22 measurement

E 25-45 MeV 45-65 MeV 65-100 MeVK.-H.Schmitt and H. Arenhovel fullM.I.Levchuk full Measurement of Tensor Analyzing Power in Deuteron Photodisintegration at the VEPP-3 Storage Ring


Preliminary results on T20, T21 and T22 measurement

E 100-150 MeV 150-250 MeV 250-400 MeVK.-H.Schmitt and H. Arenhovel fullM.I.Levchuk full




Summary

• New measurement of the tensor analyzing power compo- nents T20, T21 and T22 of two-body deuteron photodisintegration in gamma energy range 30-400 MeV and proton CM angle 20 – 30 and 80 – 100 degrees using the internal target technique has been performed.• Preliminary results of data are available and the new data consistent with the previous measurements.• In general theory describes data fairly well, but some discrepancies between calculations and data exists, especially for the T22.• Final results are expected in the nearest future.


Part of Part of people, who did the experimentpeople, who did the experiment


Dmitri Toporkov Budker Institute of Nuclear Physics Novosibirsk, Russia SPIN2005, Dubna, Russia

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