development of solid hydrogen target in riken riken t. ohnishi, h. takeda, t. suda kek s. ishimoto,...
TRANSCRIPT
Development of solid hydrogen target in RIKEN
RIKEN T. Ohnishi, H. Takeda, T. SudaKEK S. Ishimoto, S. SuzukiRCNP Y. TakahashiANL I. Tanihata
IntroductionSystemSolid hydrogen target with thin filmWindowless solid hydrogen targetSummary
Solid hydrogen target for RI beam experiment
Introduction
High energy and angular resolutions are needed.High energy and angular resolutions are needed.
1. Thin and flat target2. Uniform density3. Low background
Windowless solid hydrogen targetSolid hydrogen target with thin film
Proton elastic scattering, (p, 2p) reactions and etc..
t=1~ 5 mm d=20~ 30 mm
Requirements
Previous workTRIUNF, KEK
Cooling system: Liquid He system
For RI beam
Small system: to cover large solid angle and set easily on the beam lineLarge target: d > 20 mm
KEK: t=5~ 10 mm, d=10~ 20 mm
We develop small system and more thinner target.
Window less solid hydrogen target
TRIUNF: P. E. Knowles,et. al. Nucl. Instr. Meth. A368(1996)604.KEK : S. Ishimoto, el. al. Nucl. Instr. Meth. A480(2002)314.
System Gas Flow system
Cryostat
Vacuum Chamber
Cryostat: SUMITOMO RDK-415D Cooling power 1.5W@4KGas Flow system: Pressure ControlPt-Co resistance thermometerRadiation shield: Copper cylinder
Cell
2nd stage
1st stage
Copper block
H2 tube368mm
Solid hydrogen target with thin film300K G-H2 in/out
t=3 mm
Stycast-2850FT
PtCo thermometer
Mylar φ30 mm
300K G-H2 in/out
Stycast-2850FT
Stycast-1266PtCo thermometer
11min 20sec
Pset=60 Torr
Result
Good result
3min 40sec
Pstart=0.35 atmSolidLiquid
Bad result
T=3.7K
T=3.7K
50 μm Mylar
Liquid
Solid
Void
Liquid
Keyence LK500
H.R. Mode; 350 +/- 100 mm
Linearity; +/- 0.1% of FS
Resolution; 10 µm
Measurement of thickness
Vacuum
x
L Target
LK500
LASER MEASUREMENT; 25 MICRON MYLAR SHT
L = -0.129369 x + 64.933339
55
56
57
58
59
60
61
62
63
64
65
42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65
LASER POSITION X (mm)
LENGTH L (mm)
1ST2NDFIT DATAEmpty
80 Torr60 Torrê¸å` (FIT DATA)ê¸å` (Empty)
d = 0.6 +/- 0.05 mm
t=3 + d = 3.6 mm
3 mmd
25 μm Mylar
Experiment
R378@RIKEN
Windowless solid hydrogen target
t=7
He gas5 atm
Result
After 10 days
H2 FlowStart
H2 FlowStop
PlatesRelease
3 mm cell
Pchamber(start) ~ 10-5 Torr
Average thickness 2.7 mm
Measurement of thickness
ExperimentProton elastic scattering
Density distribution of unstable nucleiDensity distribution of unstable nuclei
RI beam
NaI array
MWDC
Vacuum chamber
Window less solid hydrogen
Si Chamber
Beam tracker
Recoil Proton: 1 ~ 100 MeV
Energy resolution < 600 keV(FWHM)
RI beam: 200 – 300 MeV/A
t = 1 mm
Summary
We have developed small solid hydrogen target system.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