So, to start things off - here's the commissioning task list as of May 8, 1996.
- Mac
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\begin{center}
{\bf Plan to Commission the CLAS Drift Chambers }
\vspace{1.0 cm}
{\bf May 8, 1996 }
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{\bf GOALS:} establish operating conditions, determine initial calibration parameters
and measure operating characteristics for the CLAS drift chambers.
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{\bf HARDWARE PREREQUISITES } - a list of hardware which must be
built, installed
and operational before drift chamber commissioning can begin.
\begin{itemize}
\item {\bf 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"
\begin{itemize}
\item Design and procurement of components
\item `Box' assembly and feedthrough placement
\item Wire stringing and daisy-chaining
\item Tests: tension, continuity, high voltage standoff
\item Gas bag, manifolds, leak sealing
\item STB and HVTB's bench-tested
\item STB, HVTB placement and testing
\item On-chamber HV cabling, testing, conditioning
\item Electronics covers installed
\item Six sector assembly (Region 1)
\item Survey points installed
\item Signals for each wire on 'scope
\end{itemize}
\item {\bf External Hardware}
\begin{itemize}
\item Gas system operational - flow tested with dummy volume
\item Laser calibration system operational
\item HV supplies and distribution boxes tested and installed
\item LV supplies tested and installed
\item ADB's tested and installed with multiplexer boards attached
\item Pulser distribution system installed
\item TDC's tested and installed
\item Cabling ADB to TDC
\item Cabling TDC crate to DAQ
\item Cosmic ray trigger installed
\item Cabling Level 1 trigger to TDC common stop
\end{itemize}
\item {\bf Installation } - all chambers installed and surveyed with
signal, low voltage and high voltage cables connected, and gas flowing.
\begin{itemize}
\item Pre-installing signal and low voltage cables
\item Attachments placed on cryostats
\item Installation fixtures built and in place
\item Clock and dock (Region 1)
\item Tension transfer (Region 2)
\item Tension measurement
\item Surveying chambers relative to toroidal coordinate system
\item Unrolling high voltage cables
\item HV, LV and signal cables connected to chambers
\item Grounding scheme implemented
\item Making ``dry-gas" connections
\item Gas lines connected to manifolds - all flow and safety systems working
\end{itemize}
\end{itemize}
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{\bf SOFTWARE PREREQUISITES } - a list of software programs and procedures
which must be written and installed before drift chamber commissioning can
begin.
\begin{itemize}
\item{\bf Data Acquisition} - data acquisition software must be written
and down-loaded into the FASTBUS crates' read-out controllers.
\begin{itemize}
\item A minimal readout code based upon CODA must be implemented for the
drift chamber FASTBUS TDC's.
\item The
trigger supervisor must be implemented in order to send stop signals to
the TDC's and read out and clear signals to the crates.
\item Readout software
must be down-loaded into the ROC's to convert the TDC outputs into
the event format of (IDWIRE,TIME); in particular the wire-to-electronics
map must be defined as well as the parameters needed to decode multiplexed
signals (pulse width values and tables of good and bad patterns).
\item A single event
display must be available to show which wires are firing.
\end{itemize}
\item{\bf 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.
\begin{itemize}
\item Calibration analysis programs which analyze the data to determine
the constants: time delays from pulse calibration analysis and
drift velocity constants from analysis of tracking data or laser
calibration data.
\item 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.
\item Hit routines: TDC to time, and 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.
\item Event analysis programs: track finder/fitter routines including
routines to determine the event start time.
\item 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.
\item Run control programs which control pulsing by reading a pulser
configuration file and pass commands on to slow controls.
\end{itemize}
\item{\bf Data Files} - calibration and monitoring banks must be defined.
There are six kinds of calibration banks:
\begin{enumerate}
\item 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, cosmic-ray runs with magnet off, sieve-slit runs, etc.).
\item Time Delays - contains cable delays, signal velocity along
wire, and time difference between DC TDC STOP and TOF TDC START.
\item Drift Velocity - parameters to determine DOCA as a function of
time for wires in each of the 34 layers, for the given {\bf B} field
setting, and for the current calibration period.
\item Translation Tables - associate each wire with its electronics;
STB, HVTB, cable number, ADB, TDC.
\item Monitoring Banks - for monitoring fast electronics (STB, ADB, TDC 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
\item Environmental Conditions - contains gas properties (pressure, temperature,
mix ratio), {\bf B} field setting, HV configuration, ADB discriminator
threshold, etc.
\end{enumerate}
\end{itemize}
\pagebreak
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{\bf 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.
\begin{itemize}
\item Verify functionality of HV, LV, gas system and de-humidifier system.
\item Turn on STB's; minimize noise level.
\item Flow gas; purge chamber, verify proper mix ratio, low $O_2$ and
$H_2O$ content.
\item Turn on HV; look at signals on 'scope.
\item Using mobile test stand (post-amps, discriminators and scalers)
measure rates.
\item Verify that ADB's are working and that TDC's are being read out.
\item Set up DAQ system and single event display.
\item Set discriminator thresholds to limit noise
hits to less than $2\%$ accidental occupancy and to prevent oscillations.
\item Pulse Level 1 trigger and ADB's, determine cable delays, search
for cross-wiring or dead channels.
\item Cross-pulse TOF and DC TDC's for synchronization.
\item Set up cosmic-ray trigger.
\item Implement single super-layer straight-line tracking.
\item Determine drift velocity parameters (esp. $V_0$ and $T_{max}$)
using automated procedures.
\item Put in other drift velocity parameters ``by hand".
\item Measure the operating characteristics of the chamber.
\begin{itemize}
\item Efficiency - determine layer efficiencies by excluding layers from fit,
determine wire efficiencies versus DOCA.
\item 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.
\item Resolution - study residual distributions versus track angle, DOCA,
layer or chamber region by the layer-excluded method and the no-layer-excluded
method.
\end{itemize}
\item Do a HV scan, measuring the layer efficiency versus voltage.
\item Choose the high voltage operating point, balancing increasing
efficiency versus current draw (and chamber lifetime).
\item Write and implement a ``standard operations procedure"
document for shift personnel.
\end{itemize}
\pagebreak
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{\bf ``BEAM-ON" COMMISSIONING: } - prepare the drift chamber system
for physics data-taking by fine-tuning the calibrations to achieve
the design goals ( $200 \mu m$ resolution, $99\%$ efficiency);
study beam-related backgrounds.
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{\bf Goals and Requirements: }
\begin{itemize}
\item Fine-tune the calibrations, e.g. study chamber misalignments
and do high-statistics study of X vs. T
\begin{itemize}
\item want {\bf B}=0 running {\bf early}
\item start at low luminosity, need {\bf thin} targets
\end{itemize}
\item Study beam-related backgrounds
\begin{itemize}
\item establish luminosity limits
\begin{itemize}
\item Chamber lifetime (total integrated current)
\item Tracking efficiency (occupancy rate)
\item Data volume (occupancy rate)
\end{itemize}
\item identify and reduce backgrounds (remember, bkgrd. is out of time)
\end{itemize}
\end{itemize}
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{\bf Tools Needed: }
\begin{itemize}
\item HV current display
\item Single event display
\item Track-independent monitors (hit/lum, etc.)
\item Mini-torus
\item Variable shielding of target (X-rays)
\end{itemize}
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