Status of the Crystal Ball Aleksandr Starostin UCLA

Works performed since the last Collaboration meeting The detector is installed on the movable frame The Crystal Ball electronics is moved to the frame and connected All crystals/PMT’s were tested on comic rays and with a radioactive source About 20 problematic/potentially problematic PMT’s were identified, most of them are fixed The Crystal Ball high voltage system was identified as a source of electronic noise in some Crystal Ball crystals. The problematic HV distributors/connectors were inspected and fixed/replaced (about 50 new connectors were installed) 9 problematic FADC were repaired/reflashed by Konorov (all of them are installed by now) The Crystal Ball pumping system was modified switching to all metal tubing

Measurements by A.Lapik Status as on February 22nd 2010 All measurements are performed with an oscilloscope All measurements are done with the beam RF off, and the target pumps off All signals were measured directly from the CB splitter

To Do List Urgent tasks: Not so urgent tasks: Check the FADC’s latency settings (ADC gates) noise in the CB signals and noisy channels Calibration of all crystals have to be verified with an Am/Be source and/or π0 peak on the hydrogen (or CH2-C) target after the DAQ settings are finalized Check the new dynamic energy range (on the shorted signal cables) of the FADC’s Not so urgent tasks: Some number of CB PMT’s (2-5) need to be fixed/replaced All spare PMT’s/bases need to be inspected and fixed The CB environmental system should be switch to the new NI DAQ and a new computer All problematic FADC need to be tested, re-flashed or sent for repair to Munich The Crystal Ball high voltage system is old and eventually need to be replaced with a newer and safer system. The designed of the new system is underway. The cost of a all-new HV system estimated to be about 14k Euro (mainly HV connectors). Your contributions financial or otherwise are welcome!