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

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

4. N. Doshita, Yamagata Univ.3 Experimental condition in terms of target - Transverse polarization by frozen spin mode at 0.62 T - Proton target - High intensity hadron beam (5 x 10 7 hadrons/second) - Smaller beam focus size High polarization, high dilution factor and long relaxation time Nuclear interaction producing secondly hadrons - temperature - heat input - target size - cooling power Cannot be polarized (only at 2.5T can be) - spin relaxation - temperature Smaller diameter target preferred - beam intensity for a bead - heat input Transverse mode with hadron beam N 2nd  R N ·N 0 + (1 - R N ) = 3 R N : Nuclear interaction rate : 40% N 0 : Number of secondly particles : 6 Total probability factor of secondly particle productions - The present system can be used

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

6. N. Doshita, Yamagata Univ.5 NH3Butanol Proton PolarizationPTPT 0.90 Dilution factor f0.1760.135 Figure of merit F17.212.1 Spin relaxation time at ~60 mK ~500h at 0.5T (SMC) ~200h at 0.42T ( GDH-Mainz,Bonn ) Selection of target material F =  (  rest  f  P T ) 2   = Material density  rest =  He   packing factor Typical polarized proton target materials used in particle physics experiments

7. 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 with -NH 3 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 Cooling power of DR

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

9. N. Doshita, Yamagata Univ.8 Specific Heat C phonon (T) =  4 N A k B ( ) DD T 3 5 12  D : Debye temperature 7 LiD ~1030K 14 NH 3 ~235K C cryocrystal (T) = ?? For NH 3,ND 3 C non-crystal (T) = ?? For butanol?, CH 2, CD 2 C L = C phonon + C cryocrystal + C non-crystal

10. N. Doshita, Yamagata Univ.9 Model for calculation of temp. variation D mm d mm - Target material : spherical shape, LiD: d=4 mm, NH 3 : d=3 mm - Beam focus = target size: circular cross section (D=30mm for muon program)  beam s -1 Total probability factor of secondly particle productions - Beam intensity :  bead in terms of one bead ·  beam · N 2nd D2D2 d2d2 =

11. N. Doshita, Yamagata Univ.10 Algorithm for the calculation  0 Q dt =  0 (T(t i-1 ) 4 - T 0 4 ) dt RKRK A n C L (T(t i-1 )) E deposit - Q + T(t i-1 )T'(t i ) = E deposit = n C L (T(t i-1 )) (T(t i ) - T'(t i-1 )) T(t i ) Beam interval: t i - t i-1 = sec = 1/  bead T 0 = 65 mK R K = 50 cm 2 K 4 /W (CrK crystal - 4 He)

12. N. Doshita, Yamagata Univ.11 Temperature variation in muon program setup NH 3 6 LiD

13. N. Doshita, Yamagata Univ.12 Hadron beam vs beam focus size for NH 3

14. N. Doshita, Yamagata Univ.13 Total heat input in the target cells mmol/sec mK Cooling power of refrigerator Q total = N 2nd · (  m ·  +  He · (1 -  )) · 2L · E MIP ·  beam This heat should be removed by Dilution refrigerator N 2nd   L E MIP  beam : Total probability factor of secondly particles : Material or helium density : Packing factor : Target cell length : 2 MeV · cm 2 /g : Beam intensity 5 mW at 75mK

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

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

17. 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 What can be done in this year for DY program? - Get information of NH3 with the system - Hadron beam test just before change to hadron program ?? - Measure total heat input and nuclear interaction rate - Measure spin relaxation time with 10 7 hadrons/s - first run for transverse mode - superradiance - Polarization, relaxation time and supperradiance