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The COMPASS polarized target for Drell-Yan physics

The COMPASS polarized target for Drell-Yan physics. Informal International Workshop on Drell-Yan physics at COMPASS 5-6 March 2007 Torino Italy. Norihiro DOSHITA. Yamagata University, Japan. Contents. - Experimental condition in terms of target.

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The COMPASS polarized target for Drell-Yan physics

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  1. The COMPASS polarized target for Drell-Yan physics Informal International Workshop on Drell-Yan physics at COMPASS 5-6 March 2007 Torino Italy Norihiro DOSHITA Yamagata University, Japan N. Doshita, Yamagata Univ.

  2. Contents - Experimental condition in terms of target - Transverse polarization with hadron beam - Present COMPASS polarized target system - Selection of target material - Limitation of target size (diameter, length) - Higher polarization and longer spin relaxation need lower temerature. Temperature heat input by high intensity hadron beam - Present Compass polarized target status - Test in 2007 run N. Doshita, Yamagata Univ.

  3. Total probability factor of secondly particle productions N2nd = RN ·N0 +(1 - RN) = 3 RN: Nuclear interaction rate : 40% N0: Number ofsecondly particles : 6 Experimental condition in terms of target Transverse mode with hadron beam - The present system can be used - Proton target High polarization, high dilution factor and long relaxation time - Transverse polarization by frozen spin mode at 0.62 T • spin relaxation • - temperature Cannot be polarized (only at 2.5T can be) - High intensity hadron beam (5 x 107 hadrons/second) • temperature • heat input • target size • cooling power Nuclear interaction producing secondly hadrons - Smaller beam focus size • beam intensity • for a bead • - heat input Smaller diameter target preferred N. Doshita, Yamagata Univ.

  4. Present COMPASS polarized target 2.5 T solenoid 0.62T dipole magnet Dilution refrigerator (~60 mK in minxing chamber) 180 mrad acceptance beam Three target cells (30 + 60 + 30 cm) mwave cavity N. Doshita, Yamagata Univ.

  5. F = r(arest f PT)2 r= Material density arest = rk/(rk + rHe(1-k)) k : packing factor Selection of target material Typical polarized proton target materials used in particle physics experiments N. Doshita, Yamagata Univ.

  6. Limitation of target cell size Sould be considered heat input by high intensity of hadron beam • Diameter beam intensity Temperature • in terms of a bead of material bead • Length total heat  Temperature • input into cells of Mixing chamber Cooling power of DR Investigate the possibility of -smaller beam focus size and target cell -higher beam intensity via -temperature variation of the material -total heat input into Mixing chamber with -NH3 N. Doshita, Yamagata Univ.

  7. Heat flow diagram heat flow T Temperature of target material MIP 2 MeV·cm2/g = constant Temperature of Mixing chamber N. Doshita, Yamagata Univ.

  8. 12 T 3 Cphonon(T) = 4 NA kB( ) 5 D Specific Heat CL = Cphonon + Ccryocrystal + Cnon-crystal D : Debye temperature 7LiD ~1030K 14NH3 ~235K Ccryocrystal(T) = ?? For NH3 ,ND3 Cnon-crystal(T) = ?? For butanol?, CH2, CD2 N. Doshita, Yamagata Univ.

  9. d2 • Beam intensity : Ibead • in terms of one bead = · Ibeam· N2nd D2 Model for calculation of temp. variation d mm Ibeam s-1 D mm - Target material : spherical shape, LiD: d=4 mm, NH3: d=3 mm - Beam focus = target size: circular cross section (D=30mm for muon program) Total probability factor of secondly particle productions N. Doshita, Yamagata Univ.

  10. Edeposit - Q T'(ti)= + T(ti-1) n CL(T(ti-1)) Algorithm for the calculation Beam interval: ti - ti-1 =  sec = 1/Ibead Edeposit = n CL(T(ti-1)) (T(ti) - T'(ti-1)) T(ti)   0 Q dt = 0 (T(ti-1)4 - T04) dt A T0 = 65 mK RK RK = 50 cm2K4/W (CrK crystal - 4He) N. Doshita, Yamagata Univ.

  11. Temperature variation in muon program setup NH3 6LiD N. Doshita, Yamagata Univ.

  12. Hadron beam vs beam focus size for NH3 N. Doshita, Yamagata Univ.

  13. N2nd : Total probability factor of secondly particles r : Material or helium density k : Packing factor L : Target cell length EMIP : 2 MeV· cm2/g 5 mW at 75mK Ibeam : Beam intensity Total heat input in the target cells • Qtotal = N2nd · (rm·k+rHe·(1 - k)) · 2L · EMIP · Ibeam This heat should be removed by Dilution refrigerator Cooling power of refrigerator mK mmol/sec N. Doshita, Yamagata Univ.

  14. Total heat input in the cells N. Doshita, Yamagata Univ.

  15. need - target holder - microwave cavity In the draft of proposal - NH3 as the target material -  3cm and 30cm long twin target cells are proposed with enough margin. N. Doshita, Yamagata Univ.

  16. Present COMPASS polarized target status - Only transverse run in 2007 - 4cm diameter 3 target cells - NH3 as proton target - need test of magnet - first run for transverse mode - superradiance What can be done in this year for DY program? - Get information of NH3 with the system - Polarization, relaxation time and supperradiance - Hadron beam test just before change to hadron program ?? • Measure total heat input and nuclear interaction rate • Measure spin relaxation time with 107 hadrons/s N. Doshita, Yamagata Univ.

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