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