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The result of cavity compton experiment

The result of cavity compton experiment. 2008 6/18 Yasuaki Ushio Hiroshima University. Contents. Set up at KEK – ATF Procedure of measurement Result of the experiment Summary. Optical cavity. Set up at KEK-ATF 1. 15.6m. g ray. -. e. -. beam. g detector set up. e.

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The result of cavity compton experiment

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  1. The result of cavity compton experiment 2008 6/18 Yasuaki Ushio Hiroshima University

  2. Contents • Set up at KEK – ATF • Procedure of measurement • Result of the experiment • Summary

  3. Optical cavity Set up at KEK-ATF 1 15.6m gray - e - beam gdetector set up e slit aperture ~0.26mrad In our set up, the minimum solid angle of gamma to be detected was determined to this slit aperture 0.26mrad. This value determined to one of gamma minimum energy. A gamma energy was from 16MeV to 28MeV.

  4. slit aperture ~0.26mrad Set up at KEK-ATF 2 gdetector set up gray - - e e beam light guide 300mm g ray f 15mm PMT Pure CsI scintillator lead shield UV-pass filter Pure CsI : The maximum emission wavelength : 315nm Emission decay time : 10-16ns UV-pass filter : Only pass the ultraviolet light. Emission decay time is enough to be faster than the data taking time and electron frequency. data taking time : 100ns electron frequency : 2.16MHz ~ 463 ns

  5. accuracy ~ 0.8mm Set up at KEK-ATF 3 Optical cavity electron beam Cavity position is moved Vertical Horizontal

  6. Transmitted light The appearance of light resonance signal Mirror reflectivity : 99.6% Mode locked laser PD Transmitted light (Photo diode) In this time, the optical cavity was resonated state Reflected light time (ms) 1ms Continued to change the length of the external cavity.

  7. Continued to change the length of the external cavity. Only picked up the data when the cavity was resonated. Gate was opened for 100ns. DAQ Schematic PD cavity - e 2.16MHz T = 463ns Could pass Comparator

  8. Vertical scan Z Procedure of measurement 1 - e movable table When Vertical scan, Moved the cavity to Z direction Z - e movable table See from upper direction. At horizontal, cavity was leaned at 12 degree Moved accuracy ~ 0.8mm ① Vertical scan Scanning to the laser vertical position and find the best position to observe gamma ②Horizontal scan Vertical was fixed to the best position. Scanning to the Horizontal.

  9. Timing scan pulsed laser Procedure of measurement 2 T=2.8ns 420mm - e beam - e beam ③ Timing scan Vertical and Horizontal were fixed to the best position. And turned on the switch of phase locked loop . After that scanning phase. We found the best collision point

  10. cavity Gamma Energy distribution 1 detected in experiment 15.6m g ray detector slit aperture 0.26mrad In calculation, the peak energy of a gamma is about 28MeV.In our set up, the acceptance of detector was 0.26mrad. One of gamma had 16~28 MeV energy. Our set up detected a lot of gamma at one time. So we estimated the number of gamma at the place of detector.

  11. Gamma Energy distribution 2 1 gamma 2 gamma This graph shows the appearance of gamma energy distribution. one of gamma had 16~28 MeV energy.

  12. 1 bunch : experiment g~3.3 simulated by CAIN g~ 4.5 The number of gamma transmitted power Mirror reflectivity : 99.6% stack power = 1 - 0.996 bunch distance : 2.8 ns We estimated the number of gamma to use a simulation software “CAIN”. 20 bunches : experiment g~3.1 simulated by CAINg ~ 20 In the case of 1 bunch, the number of gamma seems to consist comparing our experiment data with estimate by CAIN. However, the data of 20bunches were inconsistent.The reason of this,there was a possibility that not every electron bunches were collided.

  13. Summary ・ We observed the number of gamma about 3.3 per collision. ・The data of 1 bunch appears to be consistent with simulation data by CAIN. ・ The data of multi bunch mode was inconsistent.There was a possibility that not every electron bunches were collided. Next Plan ・The optical cavity length will be fixed at a condition of synchronization with electron cycle. And will be detected to the largest number of gamma in our set up.

  14. 1-R Mode lock laser PD Set up at KEK-ATF 16~28MeV Transmitted light was detected 420mm γray CSI Electron beam Collision angle 12 degree e beam We could observe how stored it was. Mode lock laser λ:1064nm Output : 28nJ/pulse=10W Distance of per pulse : 2.8ns = electron bunch distance (Internal cavity length : 420mm) Pulse length : 7ps Finess Mirror curvature : 210.5mm By calculation πR F = F = 780 Rate of reflection : 99.6% σ = 30 μm

  15. When we estimate the laser power in the cavity, we should use the data from transmitted light. Since the stack power estimate by input was considered inaccuracy. 1 bunch : γ~3.3 simulated by cain γ~ 4.5 The number of gamma We estimated the number of gamma to use a simulation software “cain”. 20 bunch : γ~3.1 simulated by cainγ~ 20

  16. slit aperture ~0.26mrad Set up at KEK-ATF 2 gdetector set up gray - - e e beam light guide 300mm g ray f 15mm PMT Pure CsI scintillator lead shield UV-pass filter Pure CsI : The maximum emission wavelength is about 305nm. UV-pass filter : Only pass the rapid time reaction element. The rapid time reaction element was enough to be faster than data taking time and electron frequency. data taking time : 100ns electron frequency : 2.16MHz ~ 463 ns

  17. レーザーと光学系 圧電素子でミラーの 光軸方向の位置を変化 衝突角 12度 共振器長 420mm 透過光強度を検出 →共振のモニター 反射率 99.6%

  18. 光学セットアップ

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