1. DC12 Commissioning Status GOALS: establish operating conditions, determine initial calibration parameters and measure operating characteristics for the CLAS drift chambers. HARDWARE PREREQUISITES - a list of hardware which must be built, installed and operational before drift chamber commissioning can begin. Chamber Assembly - all chambers built, strung, tested (tension, continuity, hv, gas leaks), on-board electronics tested and installed, bagged, survey points installed, on-chamber cabling done, gas flowing, hv and lv applied, “hv conditioned” and problems fixed External Hardware Installed – Gas system operational - flow tested with dummy volume – HV supplies and distribution boxes tested and installed – LV supplies tested and installed – DCRB’s tested and installed – Cabling DCRB crate to DAQ – Cabling Level 1 trigger to DCRB input April 17, 2015 DC12 Commissioning Plans Mac Mestayer 1

2. DC12 Software Commissioning April 17, 2015 DC12 Commissioning Plans Mac Mestayer 2 SOFTWARE PREREQUISITES - a list of software programs and procedures which must be written and installed before drift chamber commissioning can begin. Data Acquisition - data acquisition software must be written and down-loaded into the DCRB crates – A minimal readout code based upon CODA must be implemented for the DCRB’s – The trigger supervisor must be implemented in order to send timing signals to the DCRB’s and read out and clear signals to the crates. – Readout software must be down-loaded into the DCRB’s to convert the TDC outputs into the event format of (IDWIRE,TIME); in particular the wire-to-electronics map must be defined (NOTE: an alternate scheme of IDCHAN,TIME may be used.) – A single event display must be available to show which wires are firing.

3. DC12 Calibration: Algorithms Algorithms - algorithms must be written to determine calibration constants along with I/O routines to fill the banks and initialization routines to read the banks. Routines are also needed to calculate drift distances from raw TDC readings, and to monitor drift chamber performance. Calibration analysis programs which analyze the data to determine the drift velocity constants from analysis of tracking data Calibration initialization routines which read the calibration banks for the proper run period and which expand the data to fill the working arrays needed by the tracking programs. Hit routines: time to distance routines must be written which return the calculated drift time and drift distance given specific information about the track in question, the track length, local angle and hit position along the wire. Event analysis programs: track finder/fitter routines including routines to determine the event start time. Control programs to ramp on/off and monitor trips and current of the high voltage supplies, to monitor the low voltage readback, to monitor pressure, temperature, oxygen levels and constituency of the gas mixture, and to control pulsing of the laser or time-delay electronic pulsing system. April 17, 2015 DC12 Commissioning Plans Mac Mestayer 3

4. DC12: Calibration Data Files April 17, 2015 DC12 Commissioning Plans Mac Mestayer 4 Data Files - calibration and monitoring banks must be defined. Geometry - specify wire positions in sector and global toroidal coordinate systems. There must be special banks to contain modifications to chamber position or orientation based upon additional information (new surveys, alignment runs with magnet off, etc.). There must also be methods to correct for gravitational wire sag at event time. Time Delays - contains cable delays, signal velocity along wire, and time difference between DCRB and FTOF time stamps. Drift Velocity - parameters to determine DOCA as a function of time for wires in each of the 6 super-layers, for the given B field setting, and for the current calibration period. Status Tables – keep time history of HV, lv, wire status Translation Tables - associate each wire with its electronics; STB, HVTB, cable number, DCRB, Monitoring Banks - for monitoring fast electronics (STB, ADB, DCRB boards as well as their crates), HV and LV voltages and currents, general tracking parameters (such as number of hits per crate, per event, etc.), and tracking performance: efficiency, resolution and noise Environmental Conditions - contains gas properties (pressure, temperature, mix ratio), B field setting, HV configuration, DCRB discriminator threshold, etc.

5. DC12 Commissioning Procedures PROCEDURES: - determine that all equipment is working properly, turn on gas and voltage, measure noise level and set thresholds, pulse electronics to verify operations and measure delays, determine high voltage operating point, calibrate the drift velocity function and measure the operating characteristics of the chambers. Verify functionality of HV, LV, gas system and de-humidifier system. Turn on STB's; minimize noise level by searching for discrete sources Flow gas; purge chamber, verify proper mix ratio, low $O_2$ and $H_2O$ content. Turn on HV; look at signals and rates on DCRB scaler output Verify that DCRB's are being read out. Set up DAQ system and single event display. Set discriminator thresholds to limit noise hits to less than $1-2\%$ accidental occupancy and to prevent oscillations. Pulse trigger and DCRB's, determine cable delays, search for cross-wiring or dead channels. Cross-pulse TOF and DCRB's for synchronization. April 17, 2015 DC12 Commissioning Plans Mac Mestayer 5

6. DC12: Establish Operating Parameters April 17, 2015 DC12 Commissioning Plans Mac Mestayer 6 Measure the operating characteristics of the chamber. Efficiency - determine layer efficiencies by excluding layers from fit, determine wire efficiencies versus DOCA. Noise Level - determine random noise by number of hits not associated with tracks, study cross-talk and coherent noise by histogramming T i versus T j for all hit pairs on a track. Resolution - study residual distributions versus track angle, DOCA, layer or chamber region by the layer-excluded method and the no-layer-excluded method. Do a HV scan, measuring the layer efficiency versus voltage. Choose the high voltage operating point, balancing increasing efficiency versus current draw (and chamber lifetime). Choose the DCRB discriminator threshold Write and implement a ``standard operations procedure“ document for shift personnel.