• T. Furukawa, T. Inaniwa, Y. Iwata, K. Katagiri, K. Mizushima, K. Noda, S. Sato, T. Shirai, Y. Takei, E. Takeshita
  NIRS, Chiba-shi

Con­struc­tion of new treat­ment fa­cil­i­ty as an ex­ten­sion of the ex­ist­ing HIMAC fa­cil­i­ty, in which all treat­ment room will be equipped with a 3D pen­cil beam scan­ning sys­tem, is in progress at NIRS. The chal­lenge of this pro­ject is to re­al­ize treat­ment of a mov­ing tar­get by scan­ning ir­ra­di­a­tion, be­cause pen­cil beam scan­ning is more sen­si­tive to organ mo­tions com­pared with the con­ven­tion­al broad-beam ir­ra­di­a­tion. To ac­com­plish prac­ti­cal mov­ing tar­get ir­ra­di­a­tion, a pro­to­type of the scan­ning ir­ra­di­a­tion sys­tem was con­struct­ed and in­stalled into ex­ist­ing HIMAC physics ex­per­i­ment course. One of the most im­por­tant fea­tures of the sys­tem to be test­ed is fast scan­ning to­ward mov­ing tar­get ir­ra­di­a­tion with a rel­a­tive­ly large num­ber of res­can­nings with­in an ac­cept­able ir­ra­di­a­tion time. Com­mis­sion­ing of the pro­to­type is suc­cess­ful­ly in progress co­op­er­at­ing with high­ly sta­bi­lized beam pro­vid­ed by the HIMAC ac­cel­er­a­tor com­plex. We will re­port the de­sign of the sys­tem and the sta­tus of the beam study.

• Y. Iwata, T. Furukawa, K. Mizushima, K. Noda, T. Shirai, E. Takada, E. Takeshita
  NIRS, Chiba-shi
• T. Fujimoto, T. Kadowaki, Y. Sano, H. Uchiyama
  AEC, Chiba

Tumor ther­a­py using en­er­get­ic car­bon ions, as pro­vid­ed by the HIMAC, has been per­formed since June 1994, and more than 5000 pa­tients were treat­ed until now. With the suc­cess­ful clin­i­cal re­sults over more than ten years, we are con­struct­ing a new treat­ment fa­cil­i­ty. The new fa­cil­i­ty would have three treat­ment rooms; two of them have both hor­i­zon­tal and ver­ti­cal fixed-ir­ra­di­a­tion-ports, and the other has a ro­tat­ing-gantry-port. For all the ports, a scan­ning ir­ra­di­a­tion method is ap­plied. The new fa­cil­i­ty is con­struct­ed in con­junc­tion with the HIMAC, and heavy-ion beams will be pro­vid­ed by the HIMAC ac­cel­er­a­tors. To ful­fill re­quire­ments for the scan­ning ir­ra­di­a­tion, we pro­posed mul­ti­ple-en­er­gy op­er­a­tion with the quasi-DC ex­ten­sion of a flat top. With this op­er­a­tion, the beam en­er­gy can be suc­ces­sive­ly var­ied with­in a sin­gle syn­chrotron-cy­cle, and there­fore no en­er­gy de­grad­er or the range shifter is re­quired. The beam ac­cel­er­a­tion and ex­trac­tion tests of the mul­ti­ple-en­er­gy op­er­a­tion were suc­cess­ful­ly made. We will pre­sent the de­vel­op­ment of this op­er­a­tion as well as re­sults of the beam ac­cel­er­a­tion tests.

• K. Hatanaka, M. Fukuda, J. Nakagawa, T. Saito, T. Yorita
  RCNP, Osaka
• T. Kawaguchi
  KT Science Ltd., Akashi
• K. Noda
  NIRS, Chiba-shi
• Y. Sakemi
  CYRIC, Sendai

A scan­ning mag­net using high-tem­per­a­ture su­per­con­duc­tor (HTS) wire was de­signed, fab­ri­cat­ed, and test­ed for its suit­abil­i­ty as beam scan­ner. After suc­cess­ful cool­ing tests, the mag­net per­for­mance was stud­ied using DC and AC cur­rents. With DC cur­rent the mag­net was suc­cess­ful­ly op­er­at­ed to gen­er­ate de­signed field dis­tri­bu­tions and ef­fec­tive length. In AC mode, the mag­net was op­er­at­ed at fre­quen­cies of 30-59 Hz and a tem­per­a­ture of 77 K as well as 10-20 Hz and 20K. The power loss dis­si­pat­ed in the coils was mea­sured and com­pared with the model cal­cu­la­tions. The ob­served loss per cycle was in­de­pen­dent of the fre­quen­cy and the scal­ing law of the ex­ci­ta­tion cur­rent was con­sis­tent with the­o­ret­i­cal pre­dic­tions for hys­teretic loss­es in HTS wires.

• K. Katagiri, T. Furukawa, K. Noda, E. Takeshita
  NIRS, Chiba-shi

For the beam pro­file di­ag­no­sis of heavy ion can­cer ther­a­py in HIMAC (Heavy Ion Med­i­cal Ac­cel­er­a­tor in Chiba), a MWPC (Mul­ti-Wire Pro­por­tion­al Counter) de­tec­tor is em­ployed as a beam pro­file mon­i­tor. Due to the high rate beams (~ 10⁸ pps), a gain re­duc­tion of out­put sig­nals, which is caused by space charge ef­fects, have been ob­served in the scan­ning beam ex­per­i­ments at HIMAC. In order to re­duce the gain re­duc­tion by op­ti­miz­ing the pa­ram­e­ters of MWPCs in­clud­ing anode ra­dius, and dis­tance be­tween elec­trodes, a nu­mer­i­cal cal­cu­la­tion code was de­vel­oped by em­ploy­ing two-di­men­sion­al fluid model. In order to un­der­stand the re­la­tions be­tween the gain re­duc­tion and space charge dis­tri­bu­tion, the tem­po­ral evo­lu­tion of the ion/elec­tron dis­tri­bu­tion were cal­cu­lat­ed for sev­er­al hun­dredμsec­onds, which is sig­nif­i­cant­ly longer than the time pe­ri­od re­quired for ions to trav­el be­tween the elec­trodes. The out­put sig­nal was also eval­u­at­ed by the cur­rent flux into the anode and com­pared with that ob­tained by the beam ex­per­i­ment at HIMAC. The de­pen­dence of the gain re­duc­tion on the MWPC pa­ram­e­ters was an­a­lyzed from these cal­cu­la­tion re­sults.

• Y. Hashimoto, T. Toyama
  J-PARC, KEK & JAEA, Ibaraki-ken
• T. Fujisawa
  AEC, Chiba
• T. Morimoto
  Morimoto Engineering, Iruma, Saitama
• T.M. Murakami, K. Noda
  NIRS, Chiba-shi
• S. Muto
  KEK, Ibaraki
• D. Ohsawa
  Kyoto University, Radioisotope Research Center, Kyoto-shi

A non­de­struc­tive beam pro­file mon­i­tor using a ni­tro­gen-molecule gas-jet sheet has been de­vel­oped for in­tense ion beams. The den­si­ty of the gas-jet sheet cor­re­sponds to 1 x 10^-3 Pa. A light emit­ted from ni­tro­gen ex­cit­ed by an ion beam col­li­sion is mea­sured with a high sen­si­tive cam­era at­tached a ra­di­a­tion hard image in­ten­si­fi­er. In tests, beam pro­files of 6 MeV/u full-stripped oxy­gen beams whose peak cur­rent was 600 μA. were mea­sured. This paper de­scribes char­ac­ter­is­tics of the in­stru­ments and the beam test re­sults.

• K. Noda, S. Fukuda, T. Furukawa, T. Himukai, T. Inaniwa, Y. Iwata, N. Kanematsu, K. Katagiri, A. Kitagawa, S. Minohara, S. Mori, T.M. Murakami, M. Muramatsu, S. Sato, T. Shirai, E. Takada, Y. Takei, E. Takeshita
  NIRS, Chiba-shi
• T. Fujimoto, Y. Sano
  AEC, Chiba

Based on more than ten years of ex­pe­ri­ence of the car­bon can­cer ther­a­py with HIMAC, we have pro­posed a new treat­ment fa­cil­i­ty for the fur­ther de­vel­op­ment of the ther­a­py with HIMAC. This fa­cil­i­ty will con­sist of three treat­ment rooms: two rooms equipped with hor­i­zon­tal and ver­ti­cal beam-de­liv­ery sys­tems and one room with a ro­tat­ing gantry. For the beam-de­liv­ery sys­tem of the new treat­ment fa­cil­i­ty, a 3D hy­brid raster-scan­ning method with gated ir­ra­di­a­tion with pa­tient's res­pi­ra­tion has been pro­posed. A R&D study has been car­ried out to­ward the prac­ti­cal use of the pro­posed method. In the R&D study, we have im­proved the beam con­trol of the size, the po­si­tion and the time struc­ture for the pro­posed scan­ning method with the ir­ra­di­a­tion gated with pa­tient's res­pi­ra­tion. Fur­ther, owing to the in­ten­si­ty up­grade of the HIMAC syn­chrotron, we can suc­cess­ful­ly ex­tend the flat­top du­ra­tion, which can com­plete one frac­tion­al ir­ra­di­a­tion with one op­er­a­tion pe­ri­od. The build­ing con­struc­tion of the new treat­ment fa­cil­i­ty will be com­plet­ed at March 2010 and treat­ment of 1st pa­tient is sched­uled at March 2011. We will re­port the re­cent progress on the new treat­ment fa­cil­i­ty pro­ject at HIMAC.

Slides

• S. Onuma, K. Mochiki
  Tokyo City University, Tokyo
• T. Adachi, A. Kiyomichi, R. Muto, H. Nakagawa, H. Someya, M. Tomizawa
  KEK, Ibaraki
• T. Kimura
  Miyazaki University, Miyazaki
• K. Noda
  NIRS, Chiba-shi
• H. Sato
  Tsukuba University, Ibaraki

J-PARC is a new ac­cel­er­a­tor fa­cil­i­ty to pro­duce MW-class high power pro­ton beams. From the main ring (MR) high en­er­gy pro­tons are ex­tract­ed in a slow ex­tract­ed mode for hadron ex­per­i­ments. The beam is re­quired with as small rip­ple as pos­si­ble to pre­vent pile­up events in par­ti­cle de­tec­tors or data ac­qui­si­tion sys­tems. We took beam tests at HIMAC using a pro­to­type sig­nal pro­cess­ing unit. In these beam tests we had rec­og­nized the im­prove­ment of the ex­tract­ed beam struc­ture by using the feed­back al­go­rithm whose pa­ram­e­ters were changed ac­cord­ing to the beam char­ac­ter­is­tics. We have de­vel­oped a new sig­nal pro­cess­ing unit for the spill feed­back con­trol of J-PARC. The unit con­sists of three sig­nal input ports (gate, spill in­ten­si­ty and resid­u­al beam in­ten­si­ty), three sig­nal out­put ports (spill con­trol mag­nets), two DSPs (power spec­trum anal­y­sis and spill feed­back con­trol), dual port mem­o­ries, FPGAs and a LAN in­ter­face (re­mote con­trol with SUZA­KU-EPICS). From Oc­to­ber 2009, this unit is being used in the beam study of J-PARC MR to check the per­for­mance of dig­i­tal fil­ter­ing, phase-shift pro­cess­ing, servo feed­back con­trol, re­al-time power spec­trum anal­y­sis and adop­tive con­trol.

• E. Takeshita, T. Furukawa, T. Inaniwa, Y. Iwata, K. Noda, S. Sato, T. Shirai
  NIRS, Chiba-shi

The de­vel­op­ment of the screen mon­i­tor sys­tem (SCN) at the Heavy Ion Med­i­cal Ac­cel­er­a­tor in Chiba (HIMAC) com­pris­es the surveil­lance of the car­bon beam. In the three-di­men­sion­al scan­ning sys­tem for the car­bon ther­a­py, the beam qual­i­ties, i.e., po­si­tion, size and in­ten­si­ty of the beam, play a sig­nif­i­cant role for the pa­tient's treat­ment. There­fore, we de­signed a se­mi-non­de­struc­tive mon­i­tor­ing sys­tem lo­cat­ed on the the high-en­er­gy beam trans­port line to mon­i­tor the beam qual­i­ties by using a thin flu­o­res­cent screen and a high-speed charge-cou­pled de­vice. The beam po­si­tion and pro­file were ob­tained from the light emit­ting dis­tri­bu­tion of the screen. The SCN was checked on the pro­to­type scan­ning sys­tem at HIMAC and suc­ceed­ed to mon­i­tor the beam re­al-time in steps of about 10 msec, cor­re­spond­ing to a 100 Hz sam­pling rate. The de­vel­op­ments steps will focus to­ward a op­er­a­tion at HIMAC's new ther­a­py fa­cil­i­ty ex­ten­sion, re­cent­ly. In the con­fer­ence, we would like to re­port on de­tails of the au­to­mat­ic beam tun­ing be­fore start­ing the treat­ment and the in­ter­lock sys­tem dur­ing ther­a­py using the SCN.

• K. Mizushima, T. Furukawa, K. Noda, T. Shirai
  NIRS, Chiba-shi

The be­ta­tron tune fluc­tu­a­tion due to the cur­rent rip­ple of power sup­plies brings the beam spill rip­ple through the sta­ble area vari­a­tion in res­o­nant slow ex­trac­tion. The ef­fect be­comes dom­i­nant es­pe­cial­ly in the case of the low beam rate ex­trac­tion. The RF-knock­out slow ex­trac­tion method is in­sen­si­tive to the tune rip­ple com­pared to the or­di­nary one be­cause it uses the dif­fu­sion with the trans­verse RF field. How­ev­er, the rip­ple ef­fect ap­pears even in the beam spill ex­tract­ed by it. The amount of the sep­a­ra­trix fluc­tu­a­tion due to the tune rip­ple de­pends on the dif­fer­ence be­tween the bare and the res­o­nant tune, and the sex­tupole mag­net­ic strength. We mea­sured the cor­re­la­tion be­tween the beam spill and the tune rip­ple which was the ar­ti­fi­cial­ly gen­er­at­ed with low and high fre­quen­cy com­po­nents of 67 Hz and 1167 Hz near those of the real cur­rent rip­ple. We con­firmed the re­duc­tion of the beam spill rip­ple by set­ting the tune away from the res­o­nance while keep­ing the sep­a­ra­trix area. The com­par­i­son be­tween the ex­per­i­men­tal re­sults, the an­a­lyt­i­cal cal­cu­la­tion and the sim­u­la­tion will be re­port­ed.

• A. Kiyomichi, T. Adachi, A. Akiyama, S. Murasugi, R. Muto, H. Nakagawa, J.-I. Odagiri, K. Okamura, H. Sato, Y. Sato, S. Sawada, H. Someya, K.H. Tanaka, M. Tomizawa, A. Toyoda
  KEK, Tsukuba
• T. Kimura
  Miyazaki University, Miyazaki
• K. Mochiki, S. Onuma
  Tokyo City University, Tokyo
• K. Noda
  NIRS, Chiba-shi

The slow ex­trac­tion beam from the J-PARC Main Ring (MR) to the Hadron Ex­per­i­men­tal Fa­cil­i­ty is used in var­i­ous nu­cle­ar and par­ti­cle physics ex­per­i­ments. A flat struc­ture and low rip­ple noise are re­quired for the spills of the slow ex­trac­tion. The spill con­trol sys­tem has been de­vel­oped for the J-PARC slow ex­trac­tion to make a flat struc­ture and small rip­ple. It con­sists of the ex­trac­tion quadrupole mag­nets and feed­back de­vice. The ex­trac­tion mag­nets con­sist of two kinds of quadrupole mag­nets, EQ (Ex­trac­tion Q-mag­net) which make flat beam and RQ (Rip­ple Q-mag­net) which re­ject the high fre­quent rip­ple noise. The feed­back sys­tem, which is using Dig­i­tal Sig­nal Pro­ces­sor (DSP), makes a ramp­ing pat­tern for EQ and RQ from spill beam mon­i­tor. The ex­trac­tion mag­nets and feed­back de­vice were in­stalled in Septem­ber 2009, and spill feed­back study were suc­cess­ful­ly start­ed from the beam time in Oc­to­ber 2009. Here we re­port the op­er­a­tion sta­tus of mag­nets and first study of beam com­mis­sion­ing with spill feed­back.

• E. Syresin, D.E. Donets, E.D. Donets, E.E. Donets, V.V. Salnikov, V.B. Shutov
  JINR, Dubna, Moscow Region
• T. Honma, M. Kanazawa, K. Noda
  NIRS, Chiba-shi

The 11C iso­topes are pro­duced in the ni­tro­gen gas tar­get ir­ra­di­at­ed by a pro­ton beam. If the ni­tro­gen tar­get con­tains 5% of hy­dro­gen, about 5·E12 methane molecules can be pro­duced each 20 min­utes. The sep­a­rat­ed methane is load­ed into the ion source. The tech­nique used for for­ma­tion of ra­dioac­tive car­bon beams was de­vel­oped and test­ed in the JINR elec­tron string ion source (ESIS) Kri­on-2. The mea­sured con­ver­sion ef­fi­cien­cy of methane molecules to car­bon ions is rather high; it cor­re­sponds to 17 % for C⁴⁺ ions. The ex­per­i­men­tal­ly ob­tained C⁴⁺ ion in­ten­si­ty in ESIS was about 2·E9 ppp. The new ES­IS-5T is under con­struc­tion in JINR now at pro­ject ion in­ten­si­ty of 6·E9 ppp. Ac­cel­er­at­ed 12C ion beams are ef­fec­tive­ly used for can­cer treat­ment at HIMAC. The positron emis­sion to­mog­ra­phy is the most ef­fec­tive way of tumor di­ag­nos­tics. The in­ten­sive ra­dioac­tive 11C ion beam could allow both these ad­van­tages to be com­bined. It could be used both for can­cer treat­ment and for on-line PET. For­ma­tion of a pri­ma­ry ra­dioac­tive ion beam at an in­ten­si­ty on the tumor tar­get of 1·E8 pps al­lows the can­cer treat­ment by the scan­ning ra­di­a­tion method and on-line dose ver­i­fi­ca­tion.