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Development of solid hydrogen target in RIKEN. RIKEN T. Ohnishi , H. Takeda, T. Suda KEK S. Ishimoto, S. Suzuki RCNP Y. Takahashi ANL I. Tanihata. Introduction System Solid hydrogen target with thin film Windowless solid hydrogen target Summary. Introduction.
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Development of solid hydrogen target in RIKEN RIKEN T. Ohnishi, H. Takeda, T. Suda KEK S. Ishimoto, S. Suzuki RCNP Y. Takahashi ANL I. Tanihata • Introduction • System • Solid hydrogen target with thin film • Windowless solid hydrogen target • Summary
Introduction Solid hydrogen target for RI beam experiment Proton elastic scattering, (p, 2p) reactions and etc.. High energy and angular resolutions are needed. Requirements • Thin and flat target • Uniform density • Low background t=1~5 mm d=20~30 mm Windowless solid hydrogen target Solid hydrogen target with thin film
Previous work TRIUNF, KEK Window less solid hydrogen target KEK: t=5~10 mm, d=10~20 mm Cooling system: Liquid He system TRIUNF: P. E. Knowles,et. al. Nucl. Instr. Meth. A368(1996)604. KEK : S. Ishimoto, el. al. Nucl. Instr. Meth. A480(2002)314. For RI beam Small system: to cover large solid angle and set easily on the beam line Large target: d > 20 mm We develop small system and more thinner target.
System Gas Flow system Cryostat Vacuum Chamber
2nd stage 368mm H2 tube 1st stage Cryostat: SUMITOMO RDK-415D Cooling power 1.5W@4K Gas Flow system: Pressure Control Pt-Co resistance thermometer Radiation shield: Copper cylinder Copper block Cell
Solid hydrogen target with thin film 300K G-H2 in/out PtCo thermometer Stycast-2850FT t=3 mm φ30 mm Mylar
300K G-H2 in/out Stycast-2850FT Stycast-1266 PtCo thermometer
Result 50 μm Mylar Good result T=3.7K Pset=60 Torr 11min 20sec Bad result Liquid T=3.7K Solid Pstart=0.35 atm 3min 40sec
Liquid Solid Liquid Void
Measurement of thickness Keyence LK500 H.R. Mode; 350 +/- 100 mm Linearity; +/- 0.1% of FS Resolution; 10 µm Vacuum LK500 x Target L
d 3 mm 25 μm Mylar t=3 + d = 3.6 mm
Experiment R378@RIKEN
Windowless solid hydrogen target He gas 5 atm t=7
Result H2 Flow Start H2 Flow Stop 3 mm cell Plates Release Pchamber(start) ~ 10-5 Torr After 10 days
Measurement of thickness Average thickness 2.7 mm
Experiment Proton elastic scattering Density distribution of unstable nuclei NaI array RI beam: 200 – 300 MeV/A Recoil Proton: 1 ~ 100 MeV MWDC Energy resolution < 600 keV(FWHM) t = 1 mm Vacuum chamber Si Chamber RI beam Window less solid hydrogen Beam tracker
Summary We have developed small solid hydrogen target system. 1: Solid hydrogen target with thin film d = 30 mm, t = 3 mm, Mylar 25,50μm Clear solid hydrogen target without void. Thickness measurement. 2: Windowless solid hydrogen target d = 30 mm, t = 3 mm Clear solid hydrogen target without void. Thickness measurement. 10 days operation Next step: More thinner window less target, t = 1 mm