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Research on a new hybrid-target for positron source in ILC

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Research on a new hybrid-target for positron source in ILC

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  1. このプレゼンテーションでは、出席者間で討論をし、アクションアイテムを作成する場合があります。PowerPoint を使って、プレゼンテーションの実行中にアクションアイテムを作成するには ... • スライドショーの実行中に control + クリック • [会議メモ] をクリック • [アクションアイテム] タブをクリック • アクションアイテムを入力 • [OK] をクリック • このようにすると、入力したアクションアイテムを集めたスライドが、プレゼンテーションの最後に自動的に作成されます。 Research on a new hybrid-target for positron source in ILC A_R&D_06 proposal T.Suwada (tsuyoshi.suwada@kek.jp) Accelerator Laboratory, KEK FJPPL Workshop 2013, 4-6 June 2013, Yonsei Univ., Seoul, Korea

  2. Collaboration Japanese Group K.Furukawa, T.Kamitani, T.Omori, M.Satoh, T.Suwada, J.Urakawa, Accelerator Laboratory, KEK K.Umemori, IMSS, KEK T. Akagi, S.Kawada, T.Takahashi, Y.Uesugi, Hiroshima University French Group A.Variola, O. Dadoun, LAL-Orsay R.Chehab, X. Artru, M. Chevallier,IPNL-Lyon FJPPL Workshop 2013, 4-6 June 2013, Yonsei Univ., Seoul, Korea

  3. Introduction • It is a challenge to construct a dedicated and also robust positron source towards the next-generation e+e- linear collider. • The present RDR-based ILC positron source uses photo-production from a long helical undulator to generate positrons. • A crystal-assisted positron source with a hybrid target would be another approach for the ILC, and this new scheme has been adopted as the CLIC positron source. • We propose that the feasibility studies based on this new scheme need to be conducted under powerful collaboration between France and Japan. FJPPL Workshop 2013, 4-6 June 2013, Yonsei Univ., Seoul, Korea

  4. An atomic undulator for generation of unpolarized positrons at CLIC and ILC • An hybrid source using an atomic undulator(first proposition for a crystal source, Proceedings of PAC, Chicago, 1989) R.Chehab, A.Artru, F.Couchot, A.R.Nyaiesh, F.Richard Simulations of a hybrid source made of Ge or Si crystals as radiators and amorphous W as converters: For Ge and Si crystals oriented on <110> axis and 1 cm thick, we had e+ accepted yields of 0.5 to 0.6 e+/e- for 0.5 Xo thick converter and 1.2 to 1.3 e+/e- for 1 Xo thick; the incident e- energy is 20 GeV R. Chehab, POSIPOL2010, KEK, June2010 FJPPL Workshop 2013, 4-6 June 2013, Yonsei Univ., Seoul, Korea

  5. New hybrid-target scheme for positron production • THE HYBRID SCHEME FOR FUTURE LINEAR COLLIDERS • Assuming thin crystal target and, hence, moderate heating in it and in order to lower the amount of energy deposited in the amorphous target and also the PEDD, the following scheme has been proposed by [R.Chehab, V.M.Strakhovenko, A.Variola] • This new scheme is the basis of the present common research between France and Japan. Sweeping Magnet Putting a drift between the 2 targets allows sweeping off the charged particles coming from the crystal; only the ϒ impinge on the amorphous target R. Chehab, POSIPOL2010, KEK, June2010 FJPPL Workshop 2013, 4-6 June 2013, Yonsei Univ., Seoul, Korea

  6. Experimental status at KEK • The first purpose is the experimental evaluation for the hybrid-target scheme. • Particularly, to estimate the positron-production efficiency, • and to evaluate the heat load on a hybrid target. • The e+-production experiments based on a hybrid target has been performed with high-energy (8-GeV) e- beam at KEK and systematic studies have been carried out on the positron-production efficiency since 2010. • The experiments on the heat load with a hybrid target has been continued from 2011, and however, they have been partially carried out as only a test experiment due to the Tohoku heavy earthquake. • The 8-GeV e- beam experiments will resume in the end of 2013 if the recovery process is going well on time. FJPPL Workshop 2013, 4-6 June 2013, Yonsei Univ., Seoul, Korea

  7. Experimental site at KEKB LINAC KEKB Rings Switchyard KEKB Linac 8-GeVe- beam 1nc/bunch upto 25Hz single bunch FJPPL Workshop 2013, 4-6 June 2013, Yonsei Univ., Seoul, Korea

  8. Experimental Setup at 3rd SY amorphous W 8 mm 18 mm 8GeV e- Sweeping Magnet 0.96T 0.75m Analyzing magnet 5 ~ 30MeV/c 1mm thick W crystal FJPPL Workshop 2013, 4-6 June 2013, Yonsei Univ., Seoul, Korea

  9. Hybrid-target configuration Converter • Hybrid scheme • Conventional scheme Crystal e- 8GeV γ positrons from the target momentum analyzed Amorphous W sweep mag 1mm-thick W Crystal on axis (aligned to the beam) off axis (not aligned to the beam) temperature at the end of the targets by thermocouples and infrared camera Amorphous W e- 8GeV amorphous Ws 1.75, 3.5, 5.25, 8, 18mm FJPPL Workshop 2013, 4-6 June 2013, Yonsei Univ., Seoul, Korea

  10. Rocking curve measurement Amorphous W 8-GV e- sweep magnet Crystal W on a goniometer rotaion in vertical plain Fitting function for the rocking curve 8 mm-thick Preliminary factor 3 enhancement positron yield (arb. unit) [mrad] angle of crystalaxis<111> w.r.t. beam (mrad) FJPPL Workshop 2013, 4-6 June 2013, Yonsei Univ., Seoul, Korea

  11. Positron yield measurement Ee- = 8 GeV, Pe+ = 20 MeV conventional e+ detected [a.u] optimum@hybrid-on hybrid-off amorphous W thickness [mm] Need more simulations for analyzing the magnet collimator , detector to evaluate e+ yields FJPPL Workshop 2013, 4-6 June 2013, Yonsei Univ., Seoul, Korea

  12. Development of thermocouple array to measure temperature rise of the target Thermocouple array fixed at the back plane of amorphous target Thermocouple 1mm x 1mm to fast data logger read temperature each 10ms temperature at equilibrium 9 thermocouples are fixed on the target with use of silver paste Total energy deposit bunch by bunch temperature variation PEDD (peak energy deposition density) information by thermocouple FJPPL Workshop 2013, 4-6 June 2013, Yonsei Univ., Seoul, Korea

  13. Correlation plot between the measured amounts of the temperature rise and the calculation results on the PEDD Preliminary Ee- = 8 GeV conventional total energy deposit optimum@hybrid-on bunch by bunch temperature variation PEDD information by thermocouple Peak energy deposition density FJPPL Workshop 2013, 4-6 June 2013, Yonsei Univ., Seoul, Korea

  14. A granular converter for a positron source using channeling • THE GRANULAR AMORPHOUS CONVERTER • As already pointed out (see P.Pugnat, P.Sievers) [J.Phys.G.Nucl.Part.Phys.29 (2003)1797-1800] a granular converter made of small spheres of ~ mm radius offers the advantages of presenting a relatively high [surface/volume] ratio which is interesting for the power dissipation. The spheres are arranged in staggered rows. A comparison has been carried out between the granular and the compact targets concerning the yield and deposited energy. • Granular converter target is a promising • candidate for effective reduction of the heat load Slide from R.Chehab/LCWS11/Granada

  15. Funding requests in 2013 FJPPL Workshop 2013, 4-6 June 2013, Yonsei Univ., Seoul, Korea

  16. Summary • The systematic studies on positron-production efficiency has been carried out with 8-GeV e- beam at KEK. • Test measurements for a thermocouple detector have been preliminary conducted, and the results should be again evaluated with a thermocouple array detector with 8-GeV e- beam. • Systematic simulations to estimate the detector acceptance are in progress with a new simulation code taking into account crystal effect. • The e+ yields and temp. rise performance in the hybrid target should be evaluated based on the experimental results and simulations including a capture system planned. • A granular amorphous converter is expected to be a promising way to effectively reduce the heat load. FJPPL Workshop 2013, 4-6 June 2013, Yonsei Univ., Seoul, Korea

  17. Buck-up slides FJPPL Workshop 2013, 4-6 June 2013, Yonsei Univ., Seoul, Korea

  18. Test results on pulse-by-pulse Temp. rise measurement (3-GeV e- beam) 3-GeV e- single-bunch beam is directly hitting at the center of target. • The pulse-by-pulse temp. measurement has been successfully performed at the rep. rate of 1Hz. • A clear signal was obtained from each thermocouple. 温度 2mm 1秒 1mm 1℃ 1s Clear temp. signal trace with a data logger has been obtained in a test measurement. FJPPL Workshop 2013, 4-6 June 2013, Yonsei Univ., Seoul, Korea

  19. Development of simulation code at LAL-Orsay + X. Artru simulation The present work is consisting in the combination of X. Artru’s program on channeling with GEANT4. The new program will be used for extended simulations and for the KEKB experiment (data analysis). O. Dadoun, POSIPOL2010, KEK, June2010 FJPPL Workshop 2013, 4-6 June 2013, Yonsei Univ., Seoul, Korea

  20. Site Set up at the KEK LinacLooking up from Down stream e- e+ Max. Ee-=8GeV FJPPL Workshop 2013, 4-6 June 2013, Yonsei Univ., Seoul, Korea

  21. pictures Sweeping magnet e- 8GeV W Crystal on the goniometer FJPPL Workshop 2013, 4-6 June 2013, Yonsei Univ., Seoul, Korea

  22. thermocoupoles attached back end pictures amorphous targets Amorphous Ws mounted on a linear stage movable stage FJPPL Workshop 2013, 4-6 June 2013, Yonsei Univ., Seoul, Korea

  23. Temperature Measurement with 8-GeV e- beam Temperature of the 8mm amorphous W targetfor the hybrid case Beam charge ~1nC/bunch, 25Hz Preliminary Temperature (degree Celsius) ΔT~32 degree Base temp. 23.3deg. Time from Beam On (Minutes) FJPPL Workshop 2013, 4-6 June 2013, Yonsei Univ., Seoul, Korea

  24. Temp. rise vs. total energy deposit Temperature at equilibrium has information for total energy deposit except for 18mm hybrid (measured) 18mm conventional target thickness is larger than shower maximum hybridon axis hybrid off axis T at equilibrium (deg.) 8mm (simulation) FJPPL Workshop 2013, 4-6 June 2013, Yonsei Univ., Seoul, Korea

  25. A GRANULAR CONVERTER FOR A POSITRON SOURCE USING CHANNELING • THE SIMULATION RESULTS • Simulations have been operated with 2 programs: VMS (V.Strakhovenko) and FOT (X.Artru); both were associated to GEANT4. Their results are in good agreement. We present in a table the comparisons between compact and granular converter giving the same e+ yield. • 1-COMPARISON: GRANULAR & COMPACT R.Chehab/LCWS11/Granada

  26. A GRANULAR CONVERTER FOR A POSITRON SOURCE USING CHANNELING • COMPARISON GRANULAR/COMPACT • The yield and total deposited • energy/incident electron have • been simulated for a compact • and a granular target • (w.r.t. the number of layers ). • We can see, here, that a granular • target with 3 layers has slightly • lower yield than the compact • one (8 mm thick) and the energy • deposited is weaker. The choice • of the 3-layer granularity is • convenient • . R.Chehab/LCWS11/Granada

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