1. Hall C Targets for 12 GeV Silviu Covrig Hall C Hall C Users Meeting January 23, 2010

2. Cryogenic Targets LH 2, LD 2, (He) Polarized Targets

3. Standard Hall C 6 GeV LH 2 Target Three loop design, at most 2 operational at any given time 7.5 liters/loop, 15 liters total 20 K, 1.5 atm, < 700 W 1-2 l/s, flow uncertainty 100% Cell length “on demand” (used 4, 8, 10, 15, 20, 25 cm long) 20 cm cell for GepIII had 20% yield reduction @ 80  A unsuitable for precision PV measurements

4. 6GeV “Standard” LH 2 Cells Designs Beam direction

5. PV LH 2 cells (G0 and Q weak ) G0 target designed @Caltech horizontal 6 liters loop, 4.6 l/s, 20 cm cell ran for 4 years in Hall C 238 ppm nominal, best was 70 ppm 0.4% yield reduction at 40  A Q weak target designed in Hall C vertical 54 liters loop, 15 l/s, 35 cm cell needs to deliver 45 ppm predicted 1.1% yield reduction @180  A

6. 12 GeV Hall C Approved Experiments ExperimentTarget LH 2, LD 2 cm Current  E12-06-1018(4)15-90 E12-06-1041050 E12-06-105420-80 E12-06-1071580 E12-07-105890 E12-07-10220,4010,85 E12-07-1011550-100 E12-09-0118(4)35-90 E12-09-0171050 E12-09-00615,4080 E12-09-0021015-50 + 2 experiments that want a 40 cm 3 He polarized target @5-30  A There are 7 different lengths, we’d like to reduce the number to 4 (makes design and maintenance easier) Question to USERS: Is 20% yield drop @80  A over 20 cm acceptable?

7. 12 GeV Hall C Polarized Targets - E12-06-110 and E12-06-121 want 40 cm of 3He polarized targets - Hall C didn’t have such a target for the 6 GeV program - The Hall A 3He target is a collaborative effort between 8 institutions - Would like to start a steering group to find a solution for Hall C (contact Patricia or me) - Essentially two solutions: 1. Duplicate the Hall A target 2. Built a new target based on the XeMed/UNH design - NH 3 polarized target ??? (UVA is interested in helping/building one, but there are no 12 GeV approved experiments in Hall C yet)

8. Hall A Polarized 3 He Target

9. March 7, 2008 Xemed LLC 9 XeMed/UNH Target loop Concept Compress polarized 3 He and deliver to 40cm long titanium target cell Commercial compressors achieve >3500 psi (238 bar) Requires compression ratio ~16, immersion in magnetic field, rubidium-free gas leaving polarizer, entrance and exit, <3% polarization loss 14 atm200 atm Recirculating at 1.0 scfm 1 cm x 40 cm titanium target cell Requires two ports, entrance and exit Getter purifier? RGA?

10. PropertyHall AUNH Polarization (%) 5560 Beam Current (  15100 Pressure (atm) 10200 Cell type Glass/sealed Ti/continuous flow Spin “UP” time (h) 74 Beam Relaxation (h -1 ) 410.1 Laser Power (W) 1501500-2500 Thickness (cm -2 ) 1.07E+221E+24 FOM (P 2 L ) 0.22E+360.55E+38