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Lead Target and Warm Septum Interface

Lead Target and Warm Septum Interface. Performance of Lead Target during e06007 Radiation for PREX, extrapolated from e06007 Short update on Septum Interface. E06007 Lead Target Performance. E06007 Pb(e,e’p) ran Mar 5-20, 2007

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Lead Target and Warm Septum Interface

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  1. Lead TargetandWarm Septum Interface • Performance of Lead Target during e06007 • Radiation for PREX, extrapolated from e06007 • Short update on Septum Interface.

  2. E06007 Lead Target Performance • E06007 Pb(e,e’p) ran Mar 5-20, 2007 • Pb/diamond target like PREX • Pb 0.17 mm (PREX 0.5 mm) • diamond 0.15 mm (same PREX) • 2 days @ 55 uA  no failure • Ramped to 85 uA  target melted ! • Ran 2nd target @ 45 uA 2 weeks  no failure • Calibrate simulations of radiation

  3. E06007 Lead Targets Pb #4 Ran 2 weeks @ 45 uA discoloration from beam (rastered) Pb #3 Ran 2 days @ 55 uA Failed near 85 uA

  4. Target Heating Considerations Multilayer Target Monolithic Target C / Pb / C t (thickness) Q Pb is an extra heat load for C. t Heat Load Temp. Indpt. of Model assumes good contact ! t Conduction t

  5. Temperature : Extrapolating from E06007 PREX heat loads diamond lead E06007 lead is 1/3 this  Temp at center ~½ PREX (not quite 1/3 ) • Did not expect e06007 melting • But if no contact, lead melts @ ~ 40 uA. (3x3 raster) • Extrapolate to PREX(assumes same contact) (indpt. of thickness) Safe: 27 uAMelt : 40 uA Guess:temp at border ~ 50 K

  6. Target Heating -- Conclusions • Want good thermal contact. • Will vacuum grease help ? • Need procedure to center target. •  Need more test beam ? e.g. “Apiezon L” Pure hydrocarbon, high conductivity, low vapor pressure

  7. Lead Radiation Lead E06007 Pb(e,e’p) Mar 5 – 20, 2007 Hours 1450 - 2010 in plot • Calibrate simulation • Extrap. to PREX Report by Bob M. & Pavel Degtiarenko: http://hallaweb.jlab.org/parity/prex/prex_rad.pdf

  8. Site boundary neutrons (photons add ~25% more) Lead e06007 Bad beam tune

  9. Factor of ~2

  10. Radiation -- conclusions • PREX: 22% yearly site boundary budget • Probably ~1/2 that (estimates are conservative) • Factor of 4 – 10 more radiation inside hall A. • But don’t use the bad beam tune experience as a guide. • May need local shielding on IOCs on downstream beamline. ( For PREX compared to e06007 ) ( last 5 days e06007 had beam scraping )

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