Design of new tagging system
for very high energy photons
T. Yorita and S. Date’
1. Recoil electron behavior calculations
2. New chamber design
3. High energy gamma tagging test
1. Recoil electron behavior calculations
2. New chamber design
3. High energy gamma tagging test
Optics and Magnets
question:
Tagging resolution?
Can low energy recoil electron survives Q magnets?
Calculation of recoil electron behavior
BL31ID
<σx’ >=14 μrad.
Reaction region
Tagging point
BL33B2
<σx’ >=58 μrad.
Reaction region
Tagging point
- LEP emits in reaction region by injected laser or X-ray
Focus point is middle of reaction region
- Trajectories of recoil electrons are tracked by Runge-Kutta method
[MeV]
Result for LEP with 350nm laser
Ｔａｇｇｅｒ
33B2
energy resolution = 15MeV
@2GeV w/ dx=100um
(23MeV w/ dx=1mm)
31B1
energy resolution = 10MeV
@2GeV w/ dx=100um
(15MeV w/ dx=1mm)
better than 33b2 case
because of small emittance
Tag.pos.[m]
Ｔａｇｇｅｒ
[MeV]
Result for LEP with X-ray
w/ dx=1mm
Tag.pos.[m]
Result for LEP with X-ray (Cont’)
BL31ID
reaction position dependence
of energy resolution
(corn of recoil electrons)
B
C
[MeV]
A
Res.~17MeV
@6GeV
w/ dx=1mm
A
B
C
Tag.pos.[m]
1. Recoil electron behavior calculations
2. New chamber design
3. High energy gamma tagging test
Current 33 LEPS chanber
Flange and thick chamber wall would be
bottlenecks for tagging up to 7.5GeV gamma
especially for 4-6GeV.
(X0=89mm for Al)
New LEPS2 chamber design
Dx~100um
Dx~1mm
Thin wall
slot
Ｔａｇｇｅｒ
New LEPS2 chamber design II
Ｔａｇｇｅｒ
Thin wall
1. Recoil electron behavior calculations
2. New chamber design
3. High energy gamma tagging test
Can low energy recoil electron survives Q magnets?
High E gamma Tagging Test at 31BM1
BM1
Long Straight Section
Test Tagger
Photon Duct
BM2
Test Tagger
(Plastic Scintillator
with FMPMT)
Gamma Counter
(Lead Glass)
Photon Shutter
Gamma Counter
Gamma stopper
Test result