Detector Overview for Hall A E89-033

overview
duties of the on-shift detector person
links

Overview

Experiment E89-033 measures ¹⁶O(e,e'p) coincidences. The Hall A HRSe arm detects electrons, and the Hall A HRSh arm detects protons. The standard detector packages in each arm use scintillators to provide time information, wire chambers to provide trajectory information, and Cerenkov detectors plus shower counters to provide particle identification information.

Signal to noise is sufficiently high for the coincidence data that particle identification is not crucial. A small pi- + p coincidence peak has been seen as a shoulder 2 ns from the e + p coincidence peak; e + pi+ coincidences are about 30 ns away. In singles data, some pi/e separation is possible in the electron arm with Cerenkov and shower counter information. In the hadron arm, the aerogel Cerenkov is only partially installed, and there is no good singles pi/p separation.

Duties

The basic duty of the on shift detector person is to make certain that the detectors are operating well. You can look at a summary of the duties listed below.

(1) Every shift
- Do the shift checklist , or review the detector parts of the checklist if someone else does it. This should be done near the beginning of each shift. Checklist instructions are available.
- The Hall A detector checklist, by B Wojtsekhowki, has been translated from Microsoft Word. It is NOT recommended that you follow the list or its instructions in detail, but they do provide some additional information, alternate ways of checking detectors, and summary lists of some histograms / HVs to check.
(2) Every run For each run, sample the data to ensure adequate detector performance.
- ESPACE is the preferred replay code. ESPACE is used to analyze data and generate HBOOK histograms. PAW is then used to examine the histograms. ESPACE instructions are available.
- For each run, based mostly on the ESPACE replay, you should fill out the run by run checklist .
- Data can be sampled with DHIST/DSPY -- this is a good check if you suspect a problem results from ESPACE rather than from the detector. However, since DHIST/DPSY accumulates across runs unless you remember to start and stop it, and since DHIST only samples a fraction of the data, it tends to be inconvenient and hard to use in practice. It is NOT recommended or required. Use DHIST/DPSY instructions for help.
(3) Every hour or so
- XSCALER displays scalers which record logical pulses from most phototubes and from logical combinations of the signals. Scalers rates should be looked at regularly during runs to check detector performance. More information is available in the detector writeups, and in the XSCALER instructions .
- Detector HV, LV... should be checked regularly. Some information can be found in the detector EPICS info and instructions and in the summary of HV procedures . Additional HV information can be found in the detector pages below, or checklist instructions; see links above.
(4) In addition, the detector person shall undertake any duties assigned by the shift leader properly related to performing an excellent physics experiment.
(5) A note about fixing problems: problems such as bad HV settings, that are obvious and can be remotely fixed should be fixed and noted in the logbook. More obscure problems that may require entries should be discussed with shift leader, run coordinator, and / or Bogdan Wojtsekhowski (Hall A staff member in charge of detectors) as appropriate. The detector person should NOT undertake random fishing expeditions.

Detector Overview for Hall A E89-033

Overview

Duties

Links