Hybrid Target R&D at KEK-LINAC
T.TakahashiHiroshima University
25 Septemer 2012LCWS2012, Arlington, TX
Collaborators:V. Strakhovenko O. Dadoun, R. Chehab, A.Variola, L. Rinolfi, O. Dadoun,T.Kamitani, T.Suwada, T.Omori, J.Urakawa,K.Furukawa, K.Umemori,M.Satoh,T.Sugimura,S.Kawada, T.Akagi, Y. Uesugi
Contents
• Status of previous experiments• Temperature measurement 2012 January• Prospects
Hybrid target for positron source
• A away to reduce thermal load in positron targets– proposed by Chehab, Variola, Strakhovenko
• -> Experimental study to – accumulate data on e+ yields, heat deposit,,,
Feasibility as a positron source for LCs
e-e+, e-, g g
e-
e+
e+
hybrid souce for CLIC
Setup
8GeV e- 1mm W crystal
Sweeping Magnet0.96T 0.75m
amorphous W8 mm18 mm
Analyzing magnet5 ~ 30MeV
pictures
e- 8GeV
W Crystal on the goniometer
Sweeping magnet
pictures
movable stage
amorphoustargets
thermocoupolesattached back end
posit
ron
yiel
d (a
rb. u
nit)
angle of crystal axis<111> w.r.t. beam (mr)
rot. in vertical plain
esweep mag
8 mm
Rocking curve
1
2
3.4 0.117.7 0.4
1 2
2 22 21 2
( )f A B Const
same for horizontal rotationPreliminary
factor 3 enhancement
e+ yield
amorphous thickness [mm]
e+ d
etec
ted
[a.u
]P=20MeV
Need simulation for analyzing the magnet collimator , detector to evaluate e+ yeilds
0 2 4 6 8 10 12 14 16 180
5
10
15
Conventional
Hybrid ON axis
Hybrid OFF axis
Detector acceptance• Simulation of the is in progress by Y.Uesugi
simulation in progress
Very Preliminary
low acceptance 0.0005e+/e- takes time for simulation
0 2 4 6 8 10 12 14 16 18 200
0.5
1
1.5
2
2.5
3
20MeVcnv
hybrid
offaxis
sim cnv
sim hybrid
sim offaxis
Target Thickness (mm)
e+ y
ield
(A.U
)
Temperature measurement w/ thermocouples
back plane of amorphous target thermocouple
approximately 1mm x 1mm
to fast data loggerread temperature each 10ms
bunch by bunch temperature variationPEDD information by thermocouple
temperature at equilibriumtotal energy deposit
Example ofTemperature Measurement
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30202530354045505560
Temperature of the 8mm amorphous target for the hybrid case
Time from Beam On (Minutes)
Tem
pera
ture
(deg
ree
Celsi
us)
Base temp. 23.3℃
DT~32℃
Preliminary
T vs total energy deposit
hybrid on axis
conventional
18mm
8mm
T at equilibrium has information for total energy deposit except for 18mm hybrid
target is thicker than shower max
hybrid off axis
T at
equ
ilibr
ium
(deg
)
(simulation)
(mea
sure
d)
bunch by bunch temp.• dT provides a measure of PEDD
hybrid on axis
conventional
hybrid off axis
Simulation
Measured
Making thermo couple array
thermocouples
temperature distribution of amorphous targetbunch by bunch bases
design in progress at Hiroshima
temperature measurementJanuary 2012
temperature measurement
e+ yields v.s. PEDD ~G4~
e- s=4.0mm
hybrid (5GeV 8GeV) s=2.5mm
e- s=1.0mm
hybrid (5GeV 8GeV) s=1.0mm
PEDD on Amorphous Target(GeV/cm^3/e-)
e+/e
-(in
DR a
pert
ure)
e+/e
-(in
DR a
pert
ure)
conventional
conventional
e- s=2.5mmconventional
s: beam size on amorphous s: beam size on crystal
e+ yields v.s. PEDD ~G4~
e- s=4.0mm
hybrid (5GeV 8GeV) s=2.5mm
e- s=1.0mm
hybrid (5GeV 8GeV) s=1.0mm
PEDD on Amorphous Target(GeV/cm^3/e-)
e+/e
-(in
DR a
pert
ure)
e+/e
-(in
DR a
pert
ure)
conventional
conventional
e- s=2.5mmconventional
s: beam size on amorphous s: beam size on crystal
Making this plot is a purpose of this experiment, but if it is the case;
A hybrid works, why not a conventional( but worthwhile studying better crystals)
summary• Systematic data for hybrid target R&D
– yield from various target thickness, momentum– G4 Simulation in progress
• energy deposit/temperature– Thermocouple array works– in progress. G4 simulation is ready.– Systematic data in next experiments
–( but we need to wait for full recovery of KEKB LINAC)
experimental site KEKB LINAC
Switch yard
8 GeV e-~ nc/bunchupto 25Hz single bunch
After the earthquake:beam recovered to 3GeV8 GeV operation expected later half of 2012