• N. Hayashizaki
  RLNR, Tokyo
• R. Kuroda, B.E. O'Rourke, N. Oshima, R. Suzuki
  AIST, Tsukuba, Ibaraki
• E.J. Minehara
  WERC, Tsuruga , Fukui

Positron that is the an­tipar­ti­cle of the elec­tron, by the spe­cif­ic char­ac­ter, can eval­u­ate va­cant spaces in mi­crostruc­ture from atom­ic level to nanome­ter level, which is dif­fi­cult in other mea­sure­ment meth­ods. In the case of high func­tion­al ma­te­ri­al, this struc­ture often re­lates di­rect­ly to the per­for­mance, and the eval­u­a­tion method that uses the positron beam is ex­pect­ed as a use­ful mea­sure­ment tool to de­vel­op a new ma­te­ri­al. If it is able to pro­duce more high-in­tense and low-en­er­gy positron beam with an ac­cel­er­a­tor, the mi­crostruc­ture eval­u­a­tion is car­ried out in prompt and high ac­cu­ra­cy for var­i­ous de­mands of the ma­te­ri­al anal­y­sis. We have stud­ied a positron pro­duc­tion sys­tem using a su­per­con­duct­ing elec­tron linac in­stead of nor­mal con­duct­ing one. Elec­tron beam ac­cel­er­at­ed with the su­per­con­duct­ing linac is ir­ra­di­at­ed on tan­ta­lum and con­vert­ed to brem­strahlung pho­tons, and positron beam is pro­duced by pair cre­ation of them. The de­signed ac­cel­er­a­tion en­er­gy of the su­per­con­duct­ing elec­tron linac is 15-40 MeV and the max­i­mum beam power is 10 kW. The sys­tem con­fig­u­ra­tion and the progress sta­tus will be pre­sent­ed.

• Y. Hosaka, R. Betto, A. Fujita, K. Sakaue, M. Washio
  RISE, Tokyo
• S. Kashiwagi
  ISIR, Osaka
• R. Kuroda
  AIST, Tsukuba, Ibaraki
• K. Ushida
  RIKEN, Saitama

We have been study­ing a pump-probe pulse ra­di­ol­y­sis as an ap­pli­ca­tion of the S-band photo cath­ode RF-Gun. Pump-probe spec­troscopy is well-known method of pulse ra­di­ol­y­sis mea­sure­ment. We had used 5MeV elec­tron beam ob­tained from the photo cath­ode RF-Gun as a pump beam, and used the white light emit­ted from Xe flash lamp or gen­er­at­ed by self-phase mod­u­la­tion in the water cell as a probe light. How­ev­er, the white probe light with high in­ten­si­ty, good sta­bil­i­ty and broad spec­trum is a key issue for pump-probe pulse ra­di­ol­y­sis. Su­per­con­tin­u­um light with pho­ton­ic crys­tal fiber (PCF) is a new tech­nique of white light gen­er­a­tion. Short pulse laser through PCF spreads its spec­trum by non­lin­ear op­ti­cal ef­fect. Su­per­con­tin­u­um light has very con­tin­u­ous spec­trum, and it is stud­ied for var­i­ous ap­pli­ca­tions re­cent­ly. For ap­ply­ing su­per­con­tin­u­um light as a probe of pulse ra­di­ol­y­sis ex­per­i­ment, we have gen­er­at­ed a su­per­con­tin­u­um ra­di­a­tion with 7 pi­cosec­onds pulse width IR (1064nm) laser and PCF, and mea­sured its prop­er­ties. The ex­per­i­men­tal re­sults of su­per­con­tin­u­um gen­er­a­tion and de­sign of a su­per­con­tin­u­um based pulse ra­di­ol­y­sis sys­tem will be pre­sent­ed.

• R. Kuroda, H. Ikeura-Sekiguchi, M. Koike, H. Ogawa, N. Sei, H. Toyokawa, K. Yamada, M.Y. Yasumoto
  AIST, Tsukuba, Ibaraki

Ad­vanced quan­tum ra­di­a­tion sources such as a laser Comp­ton scat­ter­ing X-ray source and a co­her­ent THz ra­di­a­tion source have been de­vel­oped based on an S-band com­pact elec­tron linac at AIST in Japan. The laser Comp­ton scat­ter­ing X-ray source using a TW Ti:Sa laser can gen­er­ate a hard X-ray pulse which has vari­able en­er­gy of 12 keV - 40 keV with nar­row band­width by chang­ing elec­tron en­er­gy and col­li­sion angle for med­i­cal and bi­o­log­i­cal ap­pli­ca­tions. The co­her­ent THz ra­di­a­tion source based on the elec­tron linac has been also de­vel­oped in­stead of a con­ven­tion­al laser based THz source. The de­signed THz pulse has high peak power more than 1 kW in fre­quen­cy range be­tween 0.1 - 2 THz. The THz pulse will be gen­er­at­ed with co­her­ent ra­di­a­tion such as syn­chrotron ra­di­a­tion and tran­si­tion ra­di­a­tion using an ul­tra-short elec­tron bunch with bunch length of less than 0.5 ps (rms). The co­her­ent syn­chrotron ra­di­a­tion in the THz re­gion has been al­ready gen­er­at­ed and it will be ap­plied to the THz time do­main spec­troscopy (TDS). In this work shop, we will re­port pre­sent sta­tus of our ad­vanced quan­tum ra­di­a­tion sources.

• Y. Yokoyama, T. Aoki, K. Sakaue, T. Suzuki, M. Washio, J. Yokose
  RISE, Tokyo
• H. Hayano, N. Terunuma, J. Urakawa
  KEK, Ibaraki
• S. Kashiwagi
  ISIR, Osaka
• R. Kuroda
  AIST, Tsukuba, Ibaraki

At Wase­da Uni­ver­si­ty, we have been study­ing a high qual­i­ty elec­tron beam gen­er­a­tion and its ap­pli­ca­tion ex­per­i­ments with Cs-Te pho­to­cath­ode RF-Gun. We have al­ready suc­ceed­ed in gen­er­at­ing a sta­ble high-charged sin­gle-bunch elec­tron beam. To gen­er­ate more in­tense elec­tron beam, we de­signed a mul­ti-bunch elec­tron linac and de­vel­oped the mul­ti-pulse UV laser which ir­ra­di­ates to the cath­ode. The tar­get val­ues of the num­ber of elec­tron bunch and bunch charges are 100 bunch­es/train and 800 pC/bunch, re­spec­tive­ly. In ad­di­tion, we adopt­ed the method of the am­pli­tude mod­u­la­tion of the in­ci­dent RF pulse to the S-band klystron in order to com­pen­sate the en­er­gy dif­fer­ence in each bunch be­cause of the slow rise time of ac­cel­er­a­tion volt­age in cav­i­ty and beam load­ing ef­fect in the ac­cel­er­at­ing struc­ture. In this con­fer­ence, we will re­port de­sign prop­er­ties of our mul­ti-bunch elec­tron linac, the re­sults of the mul­ti-bunch elec­tron beam di­ag­no­sis and the en­er­gy dif­fer­ence com­pen­sa­tion using the RF am­pli­tude mod­u­la­tion method.