Hybrid Target RD at KEKLINAC T Takahashi Hiroshima

Hybrid Target R&D at KEK-LINAC T. Takahashi Hiroshima University 25 Septemer 2012 LCWS 2012, 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.

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 e+ e- e+ g e+, e-, g e- • -> Experimental study to – accumulate data on e+ yields, heat deposit, , , Feasibility as a positron source for LCs

hybrid souce for CLIC

Setup 8 Ge. V e- 1 mm W crystal Sweeping Magnet 0. 96 T 0. 75 m amorphous W 8 mm 18 mm Analyzing magnet 5 ~ 30 Me. V

pictures Sweeping magnet e- 8 Ge V W Crystal on the goniometer

amorphous targets movable stage pictures thermocoupoles attached back end

Rocking curve e sweep mag positron yield (arb. unit) 8 mm rot. in vertical plain n i m y r a P i l re factor 3 enhancement angle of crystal axis<111> w. r. t. beam (mr) same for horizontal rotation

e+ yield P=20 Me. V e+ detected [a. u] 15 Conventional Hybrid ON axis 10 Hybrid OFF axis 5 0 0 5 10 15 amorphous thickness [mm] Need simulation for analyzing the magnet collimator , detector to evaluate e+ yeilds

Detector acceptance • Simulation of the is in progress by Y. Uesugi

simulation in progress 3 20 Me. V e+ yield (A. U) 2, 5 cnv hybrid 2 Very Preliminary 1, 5 1 sim cnv sim hybrid 0, 5 0 offaxis sim offaxis 0 5 10 15 20 Target Thickness (mm) low acceptance 0. 0005 e+/e- takes time for simulation

Temperature measurement w/ thermocouples back plane of amorphous target thermocouple approximately 1 mm x 1 mm to fast data logger read temperature each 10 ms temperature at equilibrium total energy deposit bunch by bunch temperature variation PEDD information by thermocouple

Temperature (degree Celsius) Example of Temperature Measurement Temperature of the 8 mm amorphous target for the hybrid case 60 55 50 45 40 35 30 25 20 y r a n i m i l re P 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 Time from Beam On (Minutes) DT～ 32℃ Base temp. 23. 3℃

T vs total energy deposit T at equilibrium (deg) (measured) T at equilibrium has information for total energy deposit except for 18 mm hybrid conventional hybrid on axis hybrid off axis 18 mm target is thicker than shower max 8 mm (simulation)

bunch by bunch temp. • d. T provides a measure of PEDD conventional Measured hybrid on axis hybrid off axis Simulation

Making thermo couple array thermocouples temperature distribution of amorphous target bunch by bunch bases design in progress at Hiroshima

temperature measurement January 2012

temperature measurement

e+ yields v. s. PEDD ~G 4~ e+/e-(in. DR DRaperture) s: beam size on amorphous s: beam size on crystal conventional e- s=4. 0 mm hybrid (5 Ge. V 8 Ge. V) s=2. 5 mm conventional e- s=2. 5 mm hybrid (5 Ge. V 8 Ge. V) s=1. 0 mm conventional e- s=1. 0 mm PEDD on Amorphous Target(Ge. V/cm^3/e-)

e+ yields v. s. PEDD ~G 4~ s: beam size on amorphous s: beam size on crystal conventional e- s=4. 0 mm e+/e-(in. DR DRaperture) hybrid (5 Ge. V 8 Ge. V) Making this plot is a purpose of this experiment, s=2. 5 mm but if it is the case; conventional e- s=2. 5 mm A hybrid works, why not a conventional （but worthwhile studying better hybrid crystals) (5 Ge. V 8 Ge. V) s=1. 0 mm conventional e- s=1. 0 mm PEDD on Amorphous Target(Ge. V/cm^3/e-)

summary • Systematic data for hybrid target R&D – yield from various target thickness, momentum G 4 Simulation in progress • energy deposit/temperature – – Thermocouple array works – in progress. G 4 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 Ge. V e～nc/bunch upto 25 Hz single bunch After the earthquake: beam recovered to 3 Ge. V 8 Ge. V operation expected later half of 2012