• K. Yamada, T. Dantsuka, M. Fujimaki, T. Fujinawa, N. Fukunishi, A. Goto, H. Hasebe, Y. Higurashi, E. Ikezawa, O. Kamigaito, M. Kase, M. Kobayashi Komiyama, H. Kuboki, K. Kumagai, T. Maie, M. Nagase, T. Nakagawa, J. Ohnishi, H. Okuno, N. Sakamoto, Y. Sato, K. Suda, M. Wakasugi, H. Watanabe, T. Watanabe, Y. Watanabe, Y. Yano, S. Yokouchi
  RIKEN, Wako, Saitama

The Ra­dioac­tive Iso­tope Beam Fac­to­ry at RIKEN Nishi­na Cen­ter is a next gen­er­a­tion fa­cil­i­ty which is ca­pa­ble of pro­vid­ing the world’s most in­tense RI beams over the whole range of atom­ic mass­es. Three new ring cy­clotrons have been con­struct­ed as post-ac­cel­er­a­tors for the ex­ist­ing fa­cil­i­ty in order to pro­vide the in­tense heavy ion beam for the RI beam pro­duc­tion by using a in-flight sep­a­ra­tion method. The beam com­mis­sion­ing of RIBF was start­ed at July 2006 and we suc­ceed­ed in the first beam ex­trac­tion from the final boost­er cy­clotron, SRC, by using 345 MeV/nu­cle­on alu­minum beam on De­cem­ber 28^th 2006. The first ura­ni­um beam with en­er­gy of 345 MeV/nu­cle­on was ex­tract­ed from the SRC on March 23^rd 2007. Var­i­ous mod­i­fi­ca­tions for equip­ments and many beam stud­ies were per­formed in order to im­prove the trans­mis­sion ef­fi­cien­cy and to gain up the beam in­ten­si­ty. Con­se­quent­ly, the world’s most in­tense 0.4 pnA ²³⁸U beam with en­er­gy of 345 MeV/nu­cle­on and 170 pnA ⁴⁸Ca beam with en­er­gy of 345 MeV/nu­cle­on have been pro­vid­ed for ex­per­i­ments.

Slides

• T. Watanabe, N. Fukunishi, M. Kase, Y. Sasaki, Y. Yano
  RIKEN, Wako

A high­ly sen­si­tive beam cur­rent mon­i­tor with an HTS (High-Tem­per­a­ture Su­per­con­duct­ing) SQUID (Su­per­con­duct­ing QUan­tum In­ter­fer­ence De­vice) and an HTS cur­rent sen­sor, that is, an HTS SQUID mon­i­tor, has been de­vel­oped for use of the RIBF (RI beam fac­to­ry) at RIKEN. Un­like other ex­ist­ing fa­cil­i­ties, the HTS SQUID mon­i­tor al­lows us to mea­sure the DC of high-en­er­gy heavy-ion beams non­de­struc­tive­ly in real time, and the beam cur­rent ex­tract­ed from the cy­clotron can be record­ed with­out in­ter­rupt­ing the beam user's ex­per­i­ments. Both the HTS mag­net­ic shield and the HTS cur­rent sen­sor were dip-coat­ed to form a Bi₂ - Sr₂ - Ca₂ - Cu₃ - O_x (Bi-2223) layer on 99.9 % MgO ce­ram­ic sub­strates. In the pre­sent work, all the fab­ri­cat­ed HTS de­vices are cooled by a low-vi­bra­tion pulse-tube re­frig­er­a­tor. These tech­nolo­gies en­abled us to down­size the sys­tem. Prior to prac­ti­cal use at the RIBF, the HTS-SQUID mon­i­tor was in­stalled in the beam trans­port line of the RIKEN ring cy­clotron to demon­strate its per­for­mance. As a re­sult, a 20 μA ⁴⁰Ar¹⁵⁺ beam in­ten­si­ty (63 MeV/u) was suc­cess­ful­ly mea­sured with a 500 nA res­o­lu­tion. De­spite the per­for­mance tak­ing place in an en­vi­ron­ment with strong gamma ray and neu­tron flux ra­di­a­tions, RF back­ground and large stray mag­net­ic fields, the mea­sure­ments were suc­cess­ful­ly car­ried out in this study. This year, the HTS SQUID mon­i­tor was up­grad­ed to have ares­o­lu­tion of 100 nA and was re­in­stalled inthe beam trans­port line, en­abling us to mea­sure a 4 μA ¹³²Xe²⁰⁺ (10.8 MeV/u) beam and a 1 μA ¹³²Xe⁴¹⁺ (50.1 MeV/u) beam used for the ac­cel­er­a­tor op­er­a­tions at RIBF. Hence, we will re­port the re­sults of the beam mea­sure­ments an the pre­sent sta­tus of the HTS SQUID mon­i­tor.

Slides

• O. Kamigaito, S. Arai, M. Fujimaki, T. Fujinawa, H. Fujisawa, N. Fukunishi, A. Goto, Y. Higurashi, E. Ikezawa, T. Kageyama, M. Kase, M. Komiyama, H. Kuboki, K. Kumagai, T. Maie, M. Nagase, T. Nakagawa, J. Ohnishi, H. Okuno, N. Sakamoto, Y. Sato, K. Suda, H. Watanabe, T. Watanabe, Y. Watanabe, K. Yamada, H. Yamasawa, Y. Yano, S. Yokouchi
  RIKEN, Wako, Saitama

In 2008, the RIKEN RI-Beam Fac­to­ry (RIBF) suc­ceed­ed in pro­vid­ing heavy ion beams of ⁴⁸Ca and ²³⁸U with 170 par­ti­cle-nano-am­pere and 0.4 par­ti­cle-nano-am­pere, re­spec­tive­ly, at an en­er­gy of 345 MeV/u. The trans­mis­sion ef­fi­cien­cy through the ac­cel­er­a­tor chain has been sig­nif­cant­ly im­proved owing to the con­tin­u­ous ef­forts paid since the first beam in 2006. From the op­er­a­tional point of view, how­ev­er, the in­ten­si­ty of the ura­ni­um beam should be much in­creased. We have, there­fore, con­struct­ed a su­per­con­duct­ing ECR ion source which is ca­pa­ble of the mi­crowave power of 28 GHz. In order to re­duce the space-charge ef­fects, the ion source was in­stalled on the high-volt­age ter­mi­nal of the Cock­croft-Wal­ton pre-in­jec­tor, where the beam from the source will be di­rect­ly in­ject­ed into the heavy-ion linac by skip­ping the RFQ pre-in­jec­tor. The test of the ion source on the plat­form has start­ed re­cent­ly with an ex­ist­ing mi­crowave source of 18 GHz. This pre-in­jec­tor will be avail­able in Oc­to­ber 2009. We will show fur­ther up­grade plan of con­struct­ing an al­ter­na­tive in­jec­tor for the RIBF, con­sist­ing of the su­per­con­duct­ing ECR ion source, an RFQ, and three DTL tanks. An RFQ linac, which has been orig­i­nal­ly de­vel­oped for the ion-im­plan­ta­tion ap­pli­ca­tion will be reused for the new in­jec­tor. Mod­i­fi­ca­tion of the RFQ as well as the de­sign study of the DTL are under progress. The new in­jec­tor, which will be ready in FY2010, aims at in­de­pen­dent op­er­a­tion of the RIBF ex­per­i­ments and su­per-heavy el­e­ment syn­the­sis.

Slides