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Hall C Targets for 12 GeV

This document discusses the cryogenic targets used in Hall C for 12 GeV experiments, including LH2, LD2, and polarized targets. It also explores the design of the LH2 cells and the need for a 40 cm 3He polarized target in Hall C.

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Hall C Targets for 12 GeV

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

  2. Cryogenic Targets LH2, LD2, (He) • Polarized Targets

  3. Standard Hall C 6 GeV LH2 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 mA • unsuitable for precision PV measurements

  4. 6GeV “Standard” LH2 Cells Designs Beam direction

  5. Qweak 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 @180mA PV LH2 cells (G0 and Qweak) 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 40mA

  6. 12 GeV Hall C Approved Experiments + 2 experiments that want a 40 cm 3He polarized target @5-30 mA 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 @80mA 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 - NH3 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 3He Target

  9. XeMed/UNH Target loop Concept Compress polarized 3He 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 atm 200 atm Requires two ports, entrance and exit 1 cm x 40 cm titanium target cell Recirculating at 1.0 scfm Getter purifier? RGA? March 7, 2008 Xemed LLC 9

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