• T. Hiromasa, M. Nakao, A. Noda, H. Souda, H. Tongu
  Kyoto ICR, Uji, Kyoto
• K. Jimbo
  Kyoto IAE, Kyoto
• T. Shirai
  NIRS, Chiba-shi

In order to achieve three di­men­sion­al crys­tal beam, laser cool­ing forces are re­quired not only in the lon­gi­tu­di­nal di­rec­tion, but also in the trans­verse di­rec­tions. With the res­o­nance cou­pling method*, trans­verse tem­per­a­ture is trans­mit­ted into lon­gi­tu­di­nal di­rec­tion, and we have al­ready demon­strat­ed hor­i­zon­tal laser cool­ing ex­per­i­men­tal­ly **. In the pre­sent paper, we de­scribe an ap­proach to ex­tend this re­sult to three di­men­sion­al cool­ing. The ver­ti­cal cool­ing re­quires that the hor­i­zon­tal os­cil­la­tion cou­ples with the ver­ti­cal os­cil­la­tion. For achiev­ing hor­i­zon­tal-ver­ti­cal cou­pling, a solenoid in elec­tron beam cool­ing ap­pa­ra­tus is uti­lized with an ex­per­i­ment (Qx=2.07,Qy=1.07). For var­i­ous solenoidal mag­net­ic fields from 0 to 40­Gauss, hor­i­zon­tal and ver­ti­cal be­ta­tron tunes are mea­sured by beam trans­fer func­tion. For a cer­tain re­gion of the solenoidal mag­net­ic field, these tunes are mixed up each other. By op­ti­miza­tion of such a cou­pling, we aim to pro­ceed to three di­men­sion­al laser cool­ing.

* H. Okamoto Phys. Rev. E 50, 4982 (1994)
** H. Souda et.al.,contribution to this conference

• M. Nakao, T. Hiromasa, A. Noda, H. Souda, H. Tongu
  Kyoto ICR, Uji, Kyoto
• M. Grieser
  MPI-K, Heidelberg
• K. Jimbo
  Kyoto IAE, Kyoto
• H. Okamoto
  HU/AdSM, Higashi-Hiroshima
• T. Shirai
  NIRS, Chiba-shi
• A.V. Smirnov
  JINR, Dubna, Moscow Region

Ex­per­i­ments of trans­verse laser cool­ing for 24Mg+ beam have been per­formed at the small ion stor­age and cool­er ring, S-LSR. It is pre­dict­ed that the lon­gi­tu­di­nal cool­ing force is trans­mit­ted to the hor­i­zon­tal di­rec­tion with syn­chro-be­ta­tron cou­pling at the res­o­nant con­di­tion*. The laser sys­tem con­sists of a 532nm pump­ing laser, a ring dye laser with vari­able wave­length around 560nm, and a fre­quen­cy dou­bler. The hor­i­zon­tal beam size and the lon­gi­tu­di­nal mo­men­tum spread were op­ti­cal­ly mea­sured by a CCD and a PAT (Post Ac­cel­er­a­tion Tube) re­spec­tive­ly**, ***. The CCD mea­sures the beam size by ob­serv­ing spon­ta­neous emis­sion from the beam and records in se­quence of 100ms time win­dows the de­vel­op­ment of the beam pro­file. The time vari­a­tion of the beam size after beam in­jec­tion in­di­cates the trans­verse cool­ing time. The ini­tial hor­i­zon­tal beam size, which was about 1mm, was de­creased by 0.13mm in 1.5s. The lon­gi­tu­di­nal mo­men­tum spread mea­sured by PAT is in­creased at the res­o­nant con­di­tion. This sug­gests trans­verse tem­per­a­ture was trans­ferred to lon­gi­tu­di­nal di­rec­tion by syn­chro-be­ta­tron cou­pling. Both mea­sure­ments de­note the hor­i­zon­tal cool­ing oc­curred only in the res­o­nant con­di­tion ****.

* H. Okamoto, Phys. Rev. {E50}, 4982 (1994)
** M. Tanabe et. al, Appl. Phys. Express 1 (2008) 028001
*** T. Ishikawa Master Thesis, Kyoto Univ.(2008)
**** H. Souda et. al., contribution to IPAC10.

• H. Souda, T. Hiromasa, M. Nakao, A. Noda, H. Tongu
  Kyoto ICR, Uji, Kyoto
• M. Grieser
  MPI-K, Heidelberg
• K. Jimbo
  Kyoto IAE, Kyoto
• H. Okamoto
  HU/AdSM, Higashi-Hiroshima
• T. Shirai
  NIRS, Chiba-shi
• A.V. Smirnov
  JINR, Dubna, Moscow Region

Trans­verse laser cool­ing with the use of a syn­chro-be­ta­tron cou­pling is ex­per­i­men­tal­ly demon­strat­ed at the ion stor­age/cool­er ring S-LSR. Bunched 40keV ²⁴Mg⁺ beams are cooled by a co-prop­a­gat­ing laser with a wave­length of 280nm. Syn­chrotron os­cil­la­tion and hor­i­zon­tal be­ta­tron os­cil­la­tion are cou­pled by an RF drift­tube at a fi­nite dis­per­sive sec­tion (D = 1.1m) in order to trans­mit lon­gi­tu­di­nal cool­ing force to the hor­i­zon­tal de­gree of free­dom*. Time evo­lu­tion of hor­i­zon­tal beam size dur­ing laser cool­ing was mea­sured by a CCD cam­era**. Hor­i­zon­tal beam sizes were re­duced by 0.13mm with­in 1.5s after in­jec­tion when the tune val­ues sat­is­fy a dif­fer­ence res­o­nance con­di­tion, ν_s - ν_h = in­te­ger, at the op­er­at­ing tunes of (ν_h, ν_v, ν_s)=(2.067, 1.104, 0.067) and (2.058, 1.101, 0.058). With­out res­o­nance con­di­tion, the size re­duc­tion was neg­li­gi­bly small. The mo­men­tum spread was 1.7x10^-4 on the res­o­nance oth­er­wise 1.2x10^-4. These re­sults show that the hor­i­zon­tal heats are trans­ferred to the lon­gi­tu­di­nal di­rec­tion through the syn­chro-be­ta­tron cou­pling with the res­o­nance con­di­tion and are cooled down by a usual lon­gi­tu­di­nal bunched beam laser cool­ing.

* H. Okamoto, Phys. Rev. E 50, 4982 (1994).
** M. Nakao et. al., contribution to this conference.

• H. Tongu, T. Hiromasa, M. Nakao, A. Noda, H. Souda
  Kyoto ICR, Uji, Kyoto
• T. Shirai
  NIRS, Chiba-shi

S-LSR is a com­pact ion stor­age and cool­er ring to in­ject beam of the 7MeV pro­ton and the 40MeV Mg+. The av­er­age vac­u­um pres­sure mea­sured by the vac­u­um gauges with­out beam was achieved up to about 4x10^-9 Pa in 2007. Many ex­per­i­ments have been car­ried out using the pro­ton and Mg beam, for ex­am­ple the one-di­men­sion­al beam or­der­ing of pro­tons uti­liz­ing the elec­tron cool­er, the ex­trac­tion tests of the short bunched beam and the laser cool­ing for the Mg beam had been per­formed. The beam life­time can be es­ti­mat­ed with the vac­u­um pres­sure or the loss-rate of the beam en­er­gy. The val­ues of the es­ti­mat­ed life­time are near­ly equal to the mea­sured life­time val­ues. The pre­sent sta­tus of the pro­ton beam life­time and the vac­u­um pres­sure is re­port­ed.