1 / 7

Lead Target

Lead Target. D. J. Margaziotis HAPPEX Collaboration Meeting 12-1-06. Lead Target Status. Pb target intended for E06-007: 208 Pb(e,e’p) 207 Tl Scheduled to run in 2007: Officially, starting April 27 Unofficially (more likely but not confirmed), starting ~February 24 E06-007:

liliha
Télécharger la présentation

Lead Target

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Lead Target D. J. Margaziotis HAPPEX Collaboration Meeting 12-1-06

  2. Lead Target Status • Pb target intended for E06-007: 208Pb(e,e’p)207Tl • Scheduled to run in 2007: • Officially, starting April 27 • Unofficially (more likely but not confirmed), starting ~February 24 • E06-007: • Study correlations and relativistic effects in nuclear medium • Measure cross sections for low-lying 207Tl states for pm < 500 MeV/c • Extract ATL for pm < 300 MeV/c • Quasi-elastic xB=1 conditions, perpendicular kinematics • Fixed q=1.0 GeV/c, =0.433 GeV; Q2=0.81 (GeV/c)2 • I = 100 µA

  3. Past Hall A Experience with Pb • Test #1 • 0.5 mm Pb foil in “beer can” cell with flowing LH2 cooling • 3 foils, at 45°, 1” apart. • First upstream foil survived I = 60 µA, with only horizontal raster • Expect single foil could take I > 60 µA with 4 x 4 mm2 raster • Test #2 • Single-slot target-ladder block designed for PREX experiment • 0.5 mm Pb foil “sandwiched” between two 0.15 mm diamond foils • Actively cooled – cryogen through block • Successfully tested with up to I = 80 µA • Calculations indicate OK with I = 100 µA • Difficulty with knowing beam spot position relative to target center • Conclusion: Pb target is feasible for I ≤ 100 µA

  4. Simulations for Target Choice • Best available Hall A resolution will not cleanly separate low-lying Tl states • Peak extraction through peak fitting necessary • A successful peak fitting procedure was developed • GEANT simulations to assess attainable Em resolution • GEANT assumed Em profile and location of states are known • Both target configurations simulated • Result: Lead-Diamond sandwich preferred solution • Peak fitting works well even with modest number of counts to be fitted provided the line shape is known well. • Em profile will be determined experimentally by measuring a clean peak from 209Bi

  5. Weighted sum Effect of Target Thickness-GEANT 0.5 mm Pb-No diamond sandwich 0.1 mm Pb-No diamond sandwich GEANT shows good peak extraction possible given good statistics Weighted sum

  6. Choice of Pb Foil Thickness-GEANT pm = 100 MeV/c missing mass spectra 0.1 mm Pb sandwich 0.2 mm Pb sandwich • 0.1 mm foil count rates too low • 0.2 mm Pb is a good compromise between resolution and statistics • 0.17 mm is effective thickness of 0.15 mm Pb foils at 30°

  7. Present Plan for E06-007 Pb Target • Single-slot target ladder block • Similar design to previously tested target block (Test #2) • Design details TBD (by target group) • Have requested active cryo-cooling • Pb sandwich: • 0.15 mm 208Pb foil • 2 x 0.15 mm diamond foils • Positioned at 30° toward HRS-p • Bi sandwich: • 0.20 mm 209Bi foil – measure line shape of a clean lead-like peak • 2 x 0.15 mm diamond foils • Positioned at 30° toward HRS-p • Other targets on ladder: • Carbon (thickness TBD) – for background studies • BeO • Beam Current: 100 µA

More Related