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J-PARC 3GeV RCS における ビーム調整 ～ 入射部におけるビームロス起源の同定

J-PARC 3GeV RCS における ビーム調整 ～ 入射部におけるビームロス起源の同定. 原田寛之 原子力機構 /J-PARC センター ビーム物理研究会 2010 ＠理研 2010 年 11 月 12 日　. J-PARC (JAEA & KEK). Linac [181 MeV at present, 400 MeV with ACS]. 3 GeV Rapid Cycling Synchrotron (RCS). Neutrino Beam Line to Kamioka.

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J-PARC 3GeV RCS における ビーム調整 ～ 入射部におけるビームロス起源の同定

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  1. J-PARC 3GeV RCSにおけるビーム調整～入射部におけるビームロス起源の同定 原田寛之 原子力機構/J-PARCセンター ビーム物理研究会2010＠理研 2010年11月12日　

  2. J-PARC (JAEA & KEK) Linac [181 MeV at present, 400 MeV with ACS] 3 GeV Rapid Cycling Synchrotron (RCS) Neutrino Beam Line to Kamioka Materials & Life Science Facility (MLF) 50 GeV Main Ring Synchrotron (MR) [30 GeV in 1st phase] Hadron Experimental Hall

  3. Design parameters of RCS Start of the beam commissioning : October 2007~

  4. H+ H- H0 H- H0 Circulating beam RCS Injection System H- 3rd foil QFL QDL 2nd foil MWPM3 To beam dump MWPM5 MWPM4 x ISEP1,2 s PB1,2 PB3,4 1st foil SB1 SB2 SB3 SB4

  5. Horizontal Painting Injection Process 3rd foil H- QFL QDL 2nd foil To beam dump MWPM3 MWPM4 MWPM5 1st foil H+ x ISEP1,2 H- s H0 PB1,2 PB3,4 Circulating beam Circulating beam SB1 SB2 SB3 SB4 x’[mrad] H- current SB x[mm] 0 93 124.1 PB -4.4 Injection Beam Painting Area time Injection period(500μsec)

  6. Horizontal Painting Injection Process 3rd foil H- QFL QDL 2nd foil To beam dump MWPM3 MWPM4 MWPM5 1st foil H+ x ISEP1,2 H- s H0 PB1,2 PB3,4 Circulating beam Circulating beam SB1 SB2 SB3 SB4 x’[mrad] H- current SB x[mm] 0 93 124.1 PB -4.4 Injection Beam Painting Area time Injection period(500μsec)

  7. Horizontal Painting Injection Process 3rd foil H- QFL QDL 2nd foil To beam dump MWPM3 MWPM4 MWPM5 1st foil H+ x ISEP1,2 H- s H0 PB1,2 PB3,4 Circulating beam Circulating beam SB1 SB2 SB3 SB4 x’[mrad] H- current SB x[mm] 0 93 124.1 PB -4.4 Injection Beam Painting Area time Injection period(500μsec)

  8. Vertical Painting Injection process y‘ y s MWPM3 MWPM5 MWPM4 VPB1 VPB2 y H+ H- 1st foil

  9. Issue of beam loss @ injection section • Radioactivity at Horizontal plane of HO branch and BPM • ~200μSv/h@20kW operation • ~1-2mSv/h@120kW operation • Radioactivity at Vertical plane of them • ~ several 10μSv/h • No change of loss monitor signal for open/close of ring collimator • Ratio of loss signal between 1pass and circulating mode @ 20kW operation is 17 →equals to calculation value of averaging foil hit counts →Must identify the source of beam loss at high radioactivity points

  10. Issue of beam loss @ RCS Injection section Ring Collimator (1) HO branch ~200μSv/h@20kW operation ~1.2mSv/h@120kW operation To H0dump H0-Q H0-Septum2 Circulating beam H0-Septum1 QDL (2) (1) (2) BPM BPM H- injection beam QFL Foil BPM ~200μSv/h@20kW operation ~2mSv/h@120kW operation Circulating beam

  11. Foil Scattering Distribution Multiple Coulomb scattering Multiple Coulomb scattering foil Nuclear scattering** Nuclear scattering (p, p),(p, n) . . . . Coulomb & nuclear scattering Coulomb & nuclear scattering rad rad By H. Hotchi Scattering angle calculation of 106 events by GEANT simulator（Foil : 300μg/cm2） 　→Loss particles at H0 branch are 1 or 2 events from particle tracking simulation 　→Full simulation with beam core should be avoided in the view point of simulation time and increasing statics Scattering angle calculation of 108 events by GEANT simulator (Foil : 300μg/cm2） 　→Select about 104 events of large scattering more than ±3mrad

  12. Horizontal Phase Space @ 150π Painting Process Foil Foil Foil 1 turn 10 turn 20 turn Foil Foil Foil 30 turn 40 turn 50 turn Foil 57 turn Length between Injection beam position and Foil edge→12mm Painting injection only for horizontal direction Particles w/ foil hit Particles w/o foil hit

  13. Particle Tracking (1turn) @150π 3mrad -3mrad Total = 2069 Total = 1144 H0 branch BPM FOIL QDL PBH3 PBH4 QFM

  14. Particle Tracking (57turn) @150π 3mrad -3mrad Total = 2293 Total = 1080 H0 branch BPM FOIL QDL PBH3 PBH4 QFM

  15. Estimation of residual radioactivity @150πpaint for horizontal QDL FOIL PBH3 PBH4 QFM BPM Total = 1926 Total = 1115 Assumption : 1W/m = 1mSv/h 1.2kW(47×108) 220144counts (1.59m) 161141counts(0.2m) 109034counts(0.1m) 105899counts (1.36m) 278μSv/h 206μSv/h 35μSv/h 20μSv/h

  16. Estimation of residual radioactivity @150πpaint for vertical Total = 310 23@1turn → 18766@circulating 18766events(0.1m)→48μSv/h Total = 319 H0 branch BPM FOIL QDL PBH3 PBH4 QFM

  17. Solution of this issue(1) Current Foil Size (110mm x 40mm) • Average Hit Count @ foil = 8.77 New Foil Size (110mm x 15mm) • Average Hit Count @ foil = 4.66 15mm 40mm

  18. 20 turn 1 turn Particles w/ foil hit Particles w/o foil hit x’[rad] y[m] x[m] y’[rad] 40 turn 60 turn 80 turn 94 turn

  19. 20 turn 1 turn Particles w/ foil hit Particles w/o foil hit x’[rad] y[m] x[m] y’[rad] 40 turn 60 turn 80 turn 94 turn

  20. Solution of this issue(2) H0-Septum1 H0 branch duct Install the new collimator and shield at H0 branch ductfor localization of this beam loss QDL

  21. Example of localization Total = 1965 Total = 1096 H0 branch BPM FOIL

  22. Example of localization Collimator Total = 1965 Total = 1306 H0 branch BPM FOIL

  23. Summary • The source of beam loss for injection section is identified as the rare events of large-scattering by the foil hits. • As the solution of this issue, foil size is smaller and beam loss is localized at new collimator system.

  24. Decay Curve of redial radioactivity1/3mode、ACmode(Foil:260μg/cm2) 1/3mode, 560nsec, 1bunch 0.255 1/3mode, 280nsec, 2bunch 0.267 ACmode, 280nsec, 2bunch 4.372 (~17times) By K.Satou & H. Harada

  25. Estimation of Loss Particle 1ターンで入射された粒子数を108として考える。周回ごとに粒子数は増加し、100μs入射では47ターン入射されるので、トータルの粒子数は47× 108である。 現在、フォイルに当たった粒子を108として大角度のイベント104を飛ばしているため、各ターンごとに規格化してやる必要がある。 規格化したロス数 = トラッキングでのロス数 × ( ヒットした数 ÷ 全体数 ) × 入射数 (例)1ターン目 100 = 100 × ( 30000 ÷ 30000 ) ×1 (例)2ターン目 200 = 100 × ( 30000 ÷ 30000 ) ×2 (例)20ターン目 1000 = 100 × ( 15000 ÷ 30000 ) ×20 (例)57ターン目 1566 = 100 × ( 10000 ÷ 30000 ) ×47

  26. Estimation of Loss Particle 47×108粒子に対するロス粒子数（入射パルス回数：47回、周回数：57回）

  27. 第2章6節 大電流ビームの空間電荷効果 ビーム出力を増強する。 ビームの空間電荷力によって発散力を生じ、粒子は電磁石による外部収束力を弱く感じる。 ベータトロン振動数の広がりを生じる。 共鳴線に抵触し、大きなビームロスを生じる。 ビーム出力100kW時、 Simpsonsのシュミレーションによるベータトロン振動数の広がり (6.40, 6.42) Δν ～ －0.4 νy = 6 垂直方向のベータトロン振動数 νy νx = 6 Laslettのチューンスプレッドの式 水平方向のベータトロン振動数 νx nt：全電流、Bf:バンチングファクター rp：陽子の古典半径、ε：エミッタンス β,γ：ローレンツファクター １次共鳴線 ２次共鳴線

  28. 第2章6節 空間電荷力の緩和～ペインティング入射 x‘ 入射軌道や周回軌道を時間的に変化させつつ、ビーム入射を行い、実空間上に一様にビームを広がらせる。 電荷密度を小さくし、空間電荷力を緩和させる。 入射ビーム x 入射ビーム y‘ ペインティング入射 Δν ～ －0.4→ －0.1 入射ビーム y 入射ビーム ε: 周回ビームエミッタンス、β,γ: リングのTwiss parameter

  29. Correction of Ring Optics Tune measured:(6.68, 6.25), Tune set:(6.64, 6.25) Dispersions estimated by looking at a rf-frequency dependence of the closed orbit Beta estimated from a response of the closed orbit for a dipole kick (STM) Curves：Design value, Dots：Measured values, Solids：Reconstructed value 1/3 ring (straight＋arc) βx, βy[m] ηx, ηy[m] s[m] We could make the optics almost fitted to the design curves with no iteration. The measured optics (tune, beta, dispersion) was reasonably well reconstructed in our accelerator model.

  30. Control of Ring Optics (νx,νy)=(6.38,6.45) on 2008/05/26 (νx,νy)=(6.40,6.42) on 2009/11/02 We can easily control the ring optics (betatron tunes and beta amplitude functions) with good accuracy!!

  31. Measurement of Response Matrix for frequency domain and Identification of Injection Phase Space x0 : injection position, x0’ : injection derivative,νx: betatron tune, αx, βx: twiss parameter @ beam monitor,n : number of turns Fourier Transform Obtain the real and imaginary part of betatron oscillation component, which have outputs by a response matrix for injection position and derivative

  32. A11 A12 A21 A22 Measurement of response matrix

  33. Correction of the injection mismatching x at the 1st foil of injection & closed orbits : adjusted by the shift bump magnet x'at the 1st foil of the injection orbit : adjusted by the injection septum magnets Injection beam Closed orbit Injection bump Mountain plot of the beam profile measured by IPM for 1-intermediate pulse injection Horizontal profile Corrected !! Adjusted so as to minimize the betatron oscillation

  34. Correction of the injection mismatching (y,y’) at the 1st foil of the injection orbit: adjusted by injection steering magnets Mountain plot of the beam profile measured by IPM for 1-intermediate pulse injection Vertical profile Corrected !! Adjusted so as to minimize the betatron oscillation

  35. Footprint of (x, x’) over the painting injection process Single-short pulse injection (25 mA peak, 560 ns long) 600ms SB PBH 500ms ○1-pass BPM 1101-1102 △PB magnet off at t5 □MWPM3-4 t0 t5 X’(rad) t0 200 p 150 p 100 p t5 ⇒~110p ⇒~163p ⇒~220p X(m)

  36. Footprint of (y, y’) over the painting injection process Single-short pulse injection (25 mA peak , 560 ns long) ○1-pass BPM 1101-1102 □MWPM3-4 600ms SB 500ms PBV Y’(rad) t0 t5 (Correlate painting) 100 p Y(m)

  37. Acceptance Simulation 30mrad -30mrad H0 branch BPM QDL PBH3 PBH4 QFM FOIL

  38. Result of Acceptance Simulation Foil Edge Loss up to branch 7mm Loss up to BPM ±30mrad Survive through the Collimator Loss at BPM Loss up to BPM Loss up to branch

  39. Acceptance Simulation for vertical 30mrad -30mrad H0 branch BPM FOIL QDL PBH3 PBH4 QFM

  40. 100π paint injection orbit x QFL QDL 1st Foil ISEP1,2 (100pi paint bump orbit ) (shift bump orbit) PB1,2 PB3,4 S SB1 SB2 SB3 SB4

  41. 150π paint injection orbit x QFL QDL 1st Foil ISEP1,2 (150pi paint bump orbit ) (shift bump orbit) PB1,2 PB3,4 S SB1 SB2 SB3 SB4

  42. 200π paint injection orbit x QFL QDL 1st Foil ISEP1,2 (200pi paint bump orbit ) (shift bump orbit) PB1,2 PB3,4 S SB1 SB2 SB3 SB4

  43. Loss Monitor signal of H0 branch@single pass mode Loss Monitor signal by K. Yamamoto Integral Values 100πpaint decrease 150πpaint 200πpaint

  44. Loss Monitor signal of H0 branch@circulating mode Loss Monitor signal by K. Yamamoto 100πpaint decrease 150πpaint 200πpaint

  45. Loss Monitor signal of BPM@single pass mode Loss Monitor signal by K. Yamamoto 100πpaint constant 150πpaint 200πpaint

  46. Loss Monitor signal of BPM@circulating mode Loss Monitor signal by K. Yamamoto 100πpaint decrease 150πpaint 200πpaint

  47. Comparison of beam loss between simulation and experiment atring inside of H0 branch

  48. Comparison of beam loss between simulation and experiment atring inside of BPM

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