• S.S. Kurennoy, A.J. Jason, H.M. Miyadera
  LANL, Los Alamos, New Mexico

We pro­pose a high-gra­di­ent lin­ear ac­cel­er­a­tor for ac­cel­er­at­ing low-en­er­gy muons and pions in a strong solenoidal mag­net­ic field. The ac­cel­er­a­tion starts im­me­di­ate­ly after col­lec­tion of pions from a tar­get by solenoidal mag­nets and brings muons to a ki­net­ic en­er­gy of about 200 MeV over a dis­tance of the order of 10 m. At this en­er­gy, both an ion­iza­tion cool­ing of the muon beam and its fur­ther ac­cel­er­a­tion in a su­per­con­duct­ing linac be­come fea­si­ble. The pro­ject pre­sents unique chal­lenges ' a very large en­er­gy spread in a high­ly di­ver­gent beam, as well as pion and muon de­cays ' re­quir­ing large lon­gi­tu­di­nal and trans­verse ac­cep­tances. One po­ten­tial so­lu­tion in­cor­po­rates a nor­mal-con­duct­ing linac con­sist­ing of in­de­pen­dent­ly fed 0-mode RF cav­i­ties with wide aper­tures closed by thin metal win­dows or grids. The guid­ing mag­net­ic field is pro­vid­ed by ex­ter­nal su­per­con­duct­ing solenoids. The cav­i­ty choice, over­all linac de­sign con­sid­er­a­tions, and sim­u­la­tion re­sults of muon ac­cel­er­a­tion are pre­sent­ed. While the pri­ma­ry ap­pli­ca­tions of such a linac are for home­land de­fense and in­dus­try, it can pro­vide muon flux­es high enough to be of in­ter­est for physics ex­per­i­ments.

• H.M. Miyadera, A.J. Jason, S.S. Kurennoy
  LANL, Los Alamos, New Mexico

Many groups are work­ing on muon ac­cel­er­a­tors for fu­ture neu­tri­no fac­to­ry and muon col­lid­ers. One of the ap­pli­ca­tions of muon ac­cel­er­a­tor is muon ra­dio­g­ra­phy which is a promis­ing method to in­ves­ti­gate large ob­jects tak­ing ad­van­tage of the long pen­e­tra­tion lengths of muons. We pro­pose a com­pact muon ac­cel­er­a­tor that has a large en­er­gy and a phase ac­cep­tance to cap­ture rel­a­tive­ly low en­er­gy pion/muon of 10 - 100 MeV and ac­cel­er­ates them to 200 MeV with­out any beam cool­ing. Like an RFQ, mixed bunch­er/ac­cel­er­a­tion mode pro­vides phase bunch­ing dur­ing the ac­cel­er­a­tion. Our cur­rent de­sign uses 805 MHz ze­ro-mode nor­mal-con­duct­ing cav­i­ties with 35 MV/m peak field*. The nor­mal con­duct­ing cav­i­ties are sur­round­ed by su­per­con­duct­ing coils that pro­duce 5 T fo­cus­ing field. We ran Monte Carlo sim­u­la­tions to op­ti­mize linac pa­ram­e­ters such as fre­quen­cy and ac­cel­er­a­tion gra­di­ent. Muon en­er­gy loss and scat­ter­ing ef­fects at the cav­i­ty win­dows are stud­ied, too. The sim­u­la­tion showed that about 10 % of the pion/muon in­ject­ed into the linac can be ac­cel­er­at­ed to 200 MeV. Fur­ther ac­cel­er­a­tion is pos­si­ble with su­per­con­duct­ing linac.

* S. Kurennoy et al., IPAC 2010.