Minutes of 59th FFIR/BDSIM meeting on 9/17/2003

The meeting was held in a room of 425 at KEK, 10:00-12:00, 9/17/2003. We discussed on the LINAC simulation and the beam dump.

(1)LINAC simulation (T. Yamamura)

(transparencies, xx pages, pdf,xxMB) Yamamura estimated an effect of non-linear optics on beam in the main LINAC, where an injection energy is 8GeV and an exit energy is 500GeV. The non-linear optics was approximated by@sextupole components (k2) in quadrupole magnets. All the quadrupoles were assumed to have k2/k1= 0.001/Ro, where Ro=20mm, and these non-linear fields were uniformly rotated between 0 and 2/3 pi like as skew magnets.

Exit positions of beam were calculated as a function of the injected ones. For an example, the non-linear effect took effect at larger injected offset than 350um (about 11 sigmax). Such large offset could be realized in a beam halo (dark current etc.).

There were suggestions as follows; The k2 should be distributed with a Gaussian-sigma of k2/k1= 0.001/Ro. Results should be presented in a phase space for various beam halos.

(2) Beam dump ( T. Tauchi and N. Delerue )

Tauchi and Nicolas investigated the beamstrahlung photon dump with a separated beam dump. Characteristics of beamstrahlung photons have been analyzed by CAIN. Total energy is the largest in case of collisions with large offsets between two beams, which is +/- 6 ~ 10 sigmay. So, the photons would be produced even if luminosity is practically zero. The dump must be designed with this largest energy deposit (1.5 times of head-on collision's energy) and beam energy of 500GeV.

The next meeting will be on 1st October, 2003,13:30 -15:30 at 3 gokan, 425 .