Bhabha Luminometer at Dafne

At Dafne IP1 (ex KLOE) has been installed the Siddharta experiment. The runs will be used also for Crab Waist Tests (Super B). Good luminosity measurements are requested.

GEM luminometer at Dafne Upgrade

Four semi anular detectors with 32 pads each with a total diameter of 20 cm have been built. The pad dimensions are 6x24(32) mm². On the other side of PCB two places for the Carioca Cards has been foreseen. The picture below on the right shows the Carioca Card assembled. A mother board for the LV and HV power supply is plugged on. The same mother board houses the connectors for LVDS signals coming from the pads.

 

assembilng the GEM luminometer

final position of LUMI on Dafne

The GEM luminometer are able to monitor also the background around the beam pipe:
in the picture below the monitor for the
electrons during the injection :
the image of background on the
32 pads and the time evolution (400 KHz @ 500 mA).

electron background

in the picture below the monitor for the positrons during the injection.
the image of background on the 32 pads and the time evolution (740 KHz @ 460 mA).

positron background

The system is able to measure the particle impact point with a precision of ≤ 1 cm essentially dominated by the pad dimensions. The picture on the right below shows the correlation of hits for Bhabha events.

acollinearitybhabha correlation