MICRON-SCALE LASER-WIRE AT THE ATF-II AT KEK COMMISSIONING AND RESULTS

We present the first results from the commissioning of the upgraded laser-wire experiment at the Accelerator Test Facility 2 (ATF-II) at KEK. A new laser transport line and beam diagnostics were used to collide 150 mJ, 167 ps long laser pulses with 1.28 GeV, 30 ps long electron bunches to measure the vertical transverse size. Additionally, a new detector was installed with a reduced area for lower background. Initial scans showing a convoluted beam size of 18.4 ± 0.4 μm were used to tune the electron beam optics and reduce this down to 8.0 ± 0.3 μm. Laser pulse energy and charge dependency were investigated showing a linear relationship in both with a minimum laser energy of 20 mJ required for adequate signal to make a laser-wire scan.