Targets for SoLID Experiments Jian-ping Chen SoLID Collaboration Meeting Feb 3-4, 2012

Cryotarget system for PVDIS 1kW Cryotarget (LH2/LD2) system with capability of solid targets in a large acceptance strong magnetic field G0 type as starting design. Target polarization due to field Polarized 3He target system for SoLID-SIDIS(n/3He) Standard type with achieved performance SoLID field effect: end cap design Improvements Polarized NH3 target system for SoLID-SIDIS(p) (conditional approved) Transverse Polarization with opening up to +-25 degrees Design underway Effects due to strong field Overview of SoLID Target Systems

50 uA on 40 cm LD 2 /LH 2, ~800 W beam power, ~ 1 KW total power Solid targets: multi-foil 12 C (optics), Al (dummy), BeO (viewer), … Large acceptance, 2 azimuthal opening, degrees angle Density fluctuations -- moderate requirement Polarization effect to be < Cryotarget: General Requirements/Considerations

G0 Style Target for SoLID

Small target polarization will introduce large false asymmetry due to double spin asymmetry Ortho-para configurations in LH2 2 protons form I=1 (ortho) and I=0 (para) state at room T, ~75% ortho, 25% para (in equilibrium) at T=20K, ~0.2% ortho, ~99.8% para (in equilibrium) only ortho state can not be polarized Chris Keith: P(ortho) ~ 50 20K, 1T P(LH2) ~ 0.1 ppm LD2: at 20K, 1T, P ~ 8 ppm (Chris Keith) When hydrogen is cooled down it will have ortho to para conversion, but the spontaneous conversion process is slow A catalyst like ferric oxide, active carbon, … can speed it up significantly It was used at the early stage in Hall A cryotarget for LH2 target Target polarization in strong magnetic field

Existing performance: luminosity: polarization: 60% polarization spin reverse: minutes Field gradients from Solenoid: need careful design on endcap to minimize fringe field existing design would require mg/cm new convention flow target would significantly reduce requirement new upgrade would increase luminosity by a factor of 4-10, can SoLID take advantage of it? Collimator design Polarized 3He Target

Main issue: large opening angle for transverse polarization +-25 degrees (cone) keep to 5T if possible no requirements on longitudinal Don Crabb Contacting both Oxford and Scientific Magnetics both can have a design satisfying these specs Scientific Magnetics, initial quick look, it can be done, cost $600K Oxford, modify from the Hall B design, give a quote to do detailed design Forces between target magnets and Solenoid: need Tosca calculation Polarized Proton (NH3) Target