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Compton Status ►Introduction ►Recent activities ►Out Look Tohru Takahashi Hiroshima University May 14 2014 AWLC2014.

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Presentation on theme: "Compton Status ►Introduction ►Recent activities ►Out Look Tohru Takahashi Hiroshima University May 14 2014 AWLC2014."— Presentation transcript:

1 Compton Status ►Introduction ►Recent activities ►Out Look Tohru Takahashi Hiroshima University May 14 2014 AWLC2014

2 Contents Brief review of KEK-Hiroshima cavity Recent progress Future Prospects

3 29 th Mar 2013 detector γ Laser cavity ATF parameter 1.3GeV 1×10 10 electron/bunch Up to 10 bunch/train 2.16×10 6 turn/s Setup at the KEK-ATF

4 The KEK-Hiroshima Cavity IP Plane Mirror Concave Mirror Plane Mirror Concave Mirror Main Parameters Circumference:1.68m Finesse:4040(Measured) Power Enhansement:1230

5 Stored Power [w] Right pol Left pol Sotred power Laser Power: 2.6kW w/ 38W fractuation 14 th Sep 2012 Stored Laser Power in the cavity must control ΔL<<110pm achieved ΔL<<16pm

6 ATF 2.16MHz ~2.6×10 8 /sec 5bunches/train 2970±20 MeV ⇒ ~120  s / train のガンマ線に相当  ray Generation e- laser  5.6ns E  [MeV]

7 Issues Power drops after ~6s suspected thermal effect on the mirrors Transmission 6s6s Beam profile is elliptic elliptic at the focalpoint too Uesugi Injection Transmission PM Monitor Focal Point

8 Systematic investigation of the profiles at the focal point Profiles at the focal point can be observed outside Pellicle mirror : (2 μm thick half mirror) ( R < 10% ) Image of the focal point Laser inLaser out Focal point in the cavity Uesugi

9 Profiles at 3 focal spot sizes 15 μm 23 μm 20 μm 26 μm 25 μm 30 μm 長軸 / 短軸長さ( σ ) [μm] axis of propagation Z [mm] (Z = 0: min. of minor axis ) ●major ■minor ●major ■minor ●major ■minor Laser profiles near the focal point Profile at Z=0 (~ focal point) Uesugi )

10 長軸 / 短軸長さ( σ ) [μm] 伝播方向 Z [mm] (短軸 σ が最小の位置を基準 Z = 0 ) ━ major ━ mainor 20 μm 25 μm 15 μm Caculation with trans. matrix Laser profiles at the focal point ●major ■minor ●major ■minor ●major ■minor ━ major ━ minor 上杉(広島大)

11 長軸 / 短軸長さ( σ ) [μm] 伝播方向 Z [mm] (短軸 σ が最小の位置を基準 Z = 0 ) ━ major ━ minor 20 μm 25 μm 15 μm Caculation with trans. matrix Laser profiles at the focal point ●major ■minor ●major ■minor ●major ■minor ━ major ━ minor 上杉(広島大) Round shape, reasonable agreement with calculation at larger laser spot size

12 Issues for high power cavity

13 Toward high power storage Treatment of high reflectivity mirrors – Clean environment at KEK-ATF area Clean booth modification of vacuum chamer More precise feedback control – High finesse test bed at Hiroshima *Beam profile does not matter unless we want to focus down to near design minimum

14 Hoist-less manipulation of the cavity hinges

15 Hoist-less manipulation of the cavity hinges

16 Laser room at Hiroshima 4Mirror cavity is set – laser resonance has been verified – preparation for high finesse in progress

17 Plan in JFY2014 A few times more power at KEK-ATF cavity – O(10) higher reflectivity -> Max. 5 times more due to the CEO – Assuming no power dissipation on mirror -> 2times more – -> 2.8kW->28kW ( more with injection efficiency ) At Hiroshima – The same mirror with used in KEK -> 13,000 power enhansement – w/ CW laser at Hiroshima (0.2W) -> 1.3kW – more power w/ laser an amplifier? – development of digital feedback proof of principle -> realization


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