Upgraded laser wire beam profile monitor

✍ Scribed by Yosuke Honda; Noboru Sasao; Sakae Araki; Yasuo Higashi; Toshiyuki Okugi; Takashi Taniguchi; Junji Urakawa; Yoshio Yamazaki; Koichiro Hirano; Masahiro Nomura; Mikio Takano; Hiroshi Sakai

• Publisher: Elsevier Science
• Year: 2005
• Tongue: English
• Weight: 464 KB
• Volume: 538
• Category: Article
• ISSN: 0168-9002
• DOI: 10.1016/j.nima.2004.08.122

✦ Synopsis

We describe in this report an upgraded version of the laser wire beam profile monitor developed at KEK to measure a low-emittance electron beam in the ATF damping ring. This monitor is based on the Compton scattering of electrons with a laser light target. A thin and intense laser beam is produced by exciting a Fabry-Perot optical cavity with a CW laser. Various improvements were made to the original setup. First, the effective laser power inside the cavity was increased by an order of magnitude, leading to a drastic increase in a signal-to-background ratio and a decrease in measurement time. Second, readout circuits were modified to separately measure beam sizes of each bunch in a multibunch beam. Third, two cavities were installed to measure both horizontal and vertical beam sizes. With this upgraded setup, measurements of electron beam emittance operated in a multi-bunch mode were carried out successfully.