I I A , C A - PDF document

日本物理学会 春の分科会 平成 1 2 年 3 月 2 4 日 於 関西大 超低速反陽子実験のための 荷電粒子蓄積トラップの開発 I I A , C A 、堀 B A 、 市岡 利康 、檜垣 浩之 正樹 、吉城F r a n z é n 健 A 、U E C C 黒田 直史 j b a r i B a l á z s 、大島 永康 、毛利 明博 、 Ｄ 、小牧 A 、山崎 A , C 黒木 健郎 研一郎 泰規 A 、東大院理 B C Ｄ 、デブレツェン大 E 東大院総合 、理研 、科警研

発表内容 （１）A S A C U S A トラップ （設計思想・性能） （２）回転電場による 電子プラズマの制御 - （３）H イオンの閉じ込めと電子冷却 （４）まとめ 今後の実験計画

The Brillouin limit E e- + p spheroidal plasma r B ω rp Radial force balance on a charged particle with mass m, charge e : – mv 2 = –eE + evB r 2 v v e 2 n = –1 + eB – m ε 0 r m r 2 r , E =enr From : v = r ω 2 ε 0 2 ≥ 2 ω p 2 + 1 ω ω 2 ω p 2 – ω c ω 2 r = 0 c r n ≤ ε 0 B (The Brillouin limit) 2m For an antiproton, this is given : B[T] 1 5 n p [cm -3 ] 2.6 x 10 9 1.3 x 10 10 Electron density should not exceed the Brillouin limit of antiproton

Profile change by an application of rotating E-field e - ～ 1 . 3 x 1 0 8 p r e s s u r e ～ 1 . 6 x 1 0 T o r r - 9 30sec 60sec 120sec

Profile difference by total charge - 1.3 x 10 e 7 - 3.6 x 10 e 7 - 5.4 x 10 e 7 p r e s s u r e ～ 1 . 2 x 1 0 T o r r - 9 6 0 s e c w a i t + 6 0 s e c r o t - E

ASACUSA Trap design Requirements solutions # Penning type trap * Stable storage and cooling of # Harmonic potential well 10 6~8 antiprotons # 10µm precision * Monitoring of plastma modes # Gold plating * Pulse length of 50keV # Trap length = 50cm antiprotons from the RFQ (Harmonic region = 10cm) = 300ns * Vacuum in the magnet bore # Oxygen free copper # AlN (high thermal conductivity) ~ 10 -12 Torr or better * Injection from RFQ # Cylindrical electrodes * Extraction of stored antiprotons # Central harmonic potential * n e + n p < 1.3 x 10 10 region ~ 10cm p ( Brillouin limit of ) * Control of plasma shape and # One segmented electrode density by rotational RF field * System control from outside # LabView + GPIB + CAMAC the area

H- cooling : raw signals -1085V -1500V -1400V H– injection H– ions E axial : 800~1000eV -900V 0V Ejection 50µs H- + e- ; 2.7 sec H- + e- ; 5.7 sec H- + e- ; 2.7 sec H- + e- ; 5.7 sec H- + e- ; 4.2sec H- + e- ; 4.2sec e- only e- only p o t e n t i a l c h a n g e

Time distribution of extracted H- (H- only) H - s i g n a l a n d i t s d i f f e r e n c i a t i o n 0.03 2.9 sec 0.025 0.02 0.015 5.7 sec 0.01 12.7 sec 0.005 0 -0.005 -5 10 -5 5 10 -5 0 0.0001 0.00015 0.0002 0.00025 time (sec)

Time distribution of extracted H- 0.03 H- only ; 2.9 sec 0.025 0.02 0.015 H- + e- ; 2.9 sec 0.01 H- + e- ; 5.7 sec 0.005 0 -0.005 -0.01 - 5 - 5 -5 10 0 5 10 0.0001 0.00015 0.0002 0.00025 time (sec) H- ～ 2x10 6 for H- only, 2.9 sec trapping e- ～ 1.5x10 8 , loaded 70 sec before H- injection

H- cooling with/without rotating field Trapping time = 2.9 sec 0.03 H- only 0.025 0.02 H- + e- ; no rot-E 0.015 0.01 H- + e- ; with rot-E 0.005 0 -0.005 - 5 - 5 -5 10 0 5 10 0.0001 0.00015 0.0002 0.00025 Time (sec) H- ～ 2x10 6 e- ～ 9x10 7 no rot-E : electrons loaded 70 sec before H- injection with rot-E : 60 sec wait 120 sec rotating field at 2MHz, 0.5V 30 sec wait before H- injection

- e ～ 1 . 3 x 1 0 8 Change in the profile 6 0 s e c w a i t + 6 0 s e c r o t - E 1.0MHz, 0.5V 0.5MHz, 0.5V 2.0MHz, 0.5V 1.5MHz, 0.5V 2.5MHz, 0.5V 3.0MHz, 0.5V

Ion beam line E i n z e l l e n s A c c e l e r a t i o n t u b e D u o p l a s ma t r o n B e a m c h o p p e r I o n s o u r c e D i p o l e ma g n e t E i n z e l l e n s t o t h e T r a p e- : ~100 eV H- : ~1.0 keV p + : ~50 keV

Luminescence detection scheme CCD : Rox 40 (1/2 inch) 0.005 lx (F1.2, normal mode) 0.0005 lx (F1.2, high sensitive mode) ZnO : emmision peak at 505nm 1/10 decay time : 4~500 ns ITO : 10 Ω transmission = 87% at 500nm can also be used as a F.C. H-,e- PC Image size : 5~6° => Zoom lens (12.5 - 75 mm ; F1.8) Degital video : DCR-TRV900 8 lx (F1.6) > 100 lx (recommended) 0.005 lx, 1000V acceleration => 4 x 10 7 electrons can be detected.

まとめ ( 1 ) A D a n d A S A C U S A p r o j e c t P r o d u c t i o n o f me V ̃ e V a n t i p r o t o n s i s e s s e n t i a l t o t h e e x p e r i me n t s . ( 2 ) D e s i g n o f t h e A S A C U S A t r a p p i n g s y s t e m - M u l t i - r i n g h a r mo n i c t r a p ( h a r mo n i c r e g i o n ～ 1 0 c m) E l e c t r o n c o o l i n g o f 1 0 a n t i p r o t o n s 6 ̃ 8 A c t i v e c o n t r o l a n d mo n i t o r i n g o f p l a s ma ( 3 ) E x p e r i me n t w i t h e l e c t r o n s - l i f e t i me me a s u r e me n t > 1 0 0 0 s e c - C e n t e r i n g o f e l e c t r o n p l a s ma s b y r o t a t i n g E - f i e l d : ø < 2 mm ( 4 ) S i mu l a t i o n e x p e r i me n t s w i t h n e g a t i v e h y d r o g e n s - e l e c t r o n c o o l i n g w a s o b s e r v e d .