D2n Analysis To Do List
From Hall A Wiki
Contents
General rules:
If you find yourself searching for something up more than a couple of times then make a wiki entry with the information
Try and keep the wiki organized sensibly - This might mean periodic consolidation of related information onto new pages - Keep the needs of others (and yourself) in mind when to add information - See if (related) information is already present in the wiki and add to it - Imagine looking at the entry 1 year from now and ask yourself: - will you know what it means? - explain/link to where the info came from, if relevant - if it only applies to a subset of runs, energies, etc, make that clear - Imagine trying to locate this information 1 year from now: - How will you be able to find it? - what terms will you search for? - have you saved the information to a logical place in the wiki?
Documentation
Run Calendar - Starting point could be the RC calendar: http://hallaweb.jlab.org/experiment/E06-014/cal.html - Feb--Mar 2009 are the relevant pages - See: https://hallaweb.jlab.org/wiki/index.php/Analysis_resources_for_d2n#Calendar.2C_Run_Periods
Target characteristics throughout the run - links to reference and 3He cell characteristics used during d2n - links to all raw target information taken during the run - table of 'processed' target information as a function of date/time - polarization direction (w/ error) - polarization value - w/ corrections applied
Run database - target and beamline information should be integrated into run database - need to be careful that we don't get a mix of 'stale' data and 'new' data - perhaps have three independent databases: - beam characteristics (needs to be consistent with db_run.dat) - target characteristics (needs to be consistent with db_run.dat) - 'run' characteristics (incl. detector info) - make sure all relevant information is in the database - 'relevant' === stuff you find yourself scanning the log book for - make a 'how-to' in the wiki - add examples that you have found useful - add 'wish-list' items for things that should maybe be added
Table of 'special runs' - Data should be pulled from run database, but it will be useful to have convenient summary tables for the following: - target 3He elastic runs - BB optics/calibration runs - LHRS optics/calibration runs - BPM calibration runs - BCM calibration runs - BigBite Cerenkov LED/gain check runs
LHRS
detector calibrations: - position determination from survey - pion rejector - energy calibration - Cerenkov - energy (# p.e.) calibration - timing, walk corrections? - timing most useful in early coincidence running to reduce backgrounds, - not sure if we have the resolution (or need) to extract particle velocity from ToF between sub-detectors - might allow for some small (negl?) improvement in background rejection
Particle ID calibrations + Basic approach is to tune one of the two PID detectors, cut on a particular particle in that one then establish cuts on the second. Iterate back and forth a couple times until the respective cuts are optimized and understood. - It will be simplest to do this process with a low p0 setting that has a good number of electrons and pions so you can see the effect of your cuts. - pion rejector - determine electron efficiency: (electrons detected)/(total electrons) vs. - 'loose/tight' cuts - spectrometer momentum, - beam energy - determine pion rejection efficiency: (pions rejected by cuts)/(pions that are mis-identified as electrons) vs. - 'loose/tight' cuts - spectrometer momentum, - beam energy - Cerenkov - energy (# p.e.) calibration - electron efficiency - pion rejection ratio
VDC/optics cross checks/calibrations: - "Bull's eye scan" BPM calibration - raster current <-> BPM calibration for raster correction - tracking efficiency checks - use 1-pass e,p elastic data and cut on proton arm so you know that an electron is - track multiplicity measurements - sieve plate reconstruction - optics target (z-target) reconstruction
Trigger efficiency - T3 vs. T4 trigger analysis
LHRS Acceptance See 'Effective Use of Hall A HRS Acceptance With R-Functions'
BigBite
detector calibrations: - position determination from survey - shower/pre-shower - energy calibration - Cerenkov - energy (# p.e.) calibration - start with second half of run period where Cerenkov was stable -- we'll work on the first half later - MWDC - plane-to-plane tracking efficiencies vs. luminosity - ie. vs. target, beam current - MWDC chamber position corrections via residual analysis - drift-time correction calibration - timing, walk corrections? - timing most useful in early coincidence running to reduce backgrounds, - not sure if we have the resolution (or need) to extract particle velocity from ToF between sub-detectors in single-arm - might allow for some small (negl?) improvement in background rejection
MWDC/optics cross checks/calibrations: - "Bull's eye scan" BPM calibration - raster current <-> BPM calibration for raster correction - tracking efficiency checks - use 1-pass e,p elastic data and cut on proton arm so you know that an electron is - track multiplicity measurement - we really want only single-track events, BB is noisy and will have a significant fraction of multi-track events: - what is 1:2:3:4:... track multiplicity for a given luminosity (and/or target?) - how does this improve when you apply geometric cuts on which blocks fired in the shower+pre-shower? - ie. project each track back to the shower plane and see if there is a hit in the associated block(s) - sieve plate reconstruction - optics target (z-target) reconstruction
Cerenkov cross checks - use software cuts on the Shower-only BigBite trigger and cross check the performance with the Shower+Cer geometric overlap trigger
Particle ID calibrations + Basic approach is to tune one of the two PID detectors, cut on a particular particle in that one then establish cuts on the second. Iterate back and forth a couple times until the respective cuts are optimized and understood. - You can start with a pretty wide momentum cut here, the low-p0 part will have a pretty high pi:electron ratio
- pion rejector - determine electron efficiency: (electrons detected)/(total electrons) vs. - 'loose/tight' cuts - spectrometer momentum, - beam energy - determine pion rejection efficiency: (pions rejected by cuts)/(pions that are mis-identified as electrons) vs. - 'loose/tight' cuts - spectrometer momentum, - beam energy - Cerenkov - energy (# p.e.) calibration - electron efficiency - pion rejection ratio
BigBite Acceptance - "shouldn't" be a problem since it drops out in asyms calculation - would be interesting to place some tight cuts and see what kind of cross sections can be extracted...
Target analysis
polarization calibration constant - cross checks between EPR, water NMR signal - polarizing gradient between target and pumping chamber N2 dilution analysis 3He pressure curve analysis 1 pass elastic 3He polarization cross checks - vs. 'SAMC' monte carlo simulation Target density and temperature analysis Target Holding field direction (compass measurements)
Beam calibrations
polarization - table/calendar with Moller results, half-wave plate changes - Compton charge asym analysis BCM calibration raster calibration/correction Check for possible asym in gate timing: see Halog 280105
Compton analysis
- Cross calibration between the Moller and Compton photon asym - linearity checks - IHWP consistency checks - correction for misbehaving power bit - cross calibration between original Saclay DAQ and new CMU DAQ - other systematics (beam position, beam charge asymmetry, ...?) - Compton asymmetry history for each beam configuration - error analysis - . . .
Direct extraction from photon aysm + MC?
And all the rest... (to be filled out later)
- check for any bleed through effects from Hall C laser
- Livetime corrections
- Radiative corrections
- False asymmetry analysis
- look at Carbon, N2, 3He (ref cell) data
- Positron backgrounds
- simulation/model - 5- and 4-pass positron runs
- 3He to neutron
d2n, g1, g2 extractions, etc. . . .
Milestones (Please add/update)
detector calibrations (LHRS + BigBite) - show reconstructed sieve plate - show reconstructed z-target for optics
particle ID calibrations - plots of pion-rejection and electron efficiency vs. PID cuts
tabulate "run-sets" for focused analysis - blocks of runs that you will need 'special' treatment - ie. different beam energy - some change to a sub-detector - ie. change in hardware, etc.
LHRS specific - 12C(e,e') cross section extraction and compare to existing data - 3He(e,e') abs. cross section extraction and compare to existing data
BigBite specific - extract prelim. asym in medium momentum bin (ie. not too low cross section, but not too large pion contamination) - show it changes sign with target flip - show it changes sign with IHWP flip
Compton calibrations - power bit corrections - IHWP sanity checks - Compton/Moller cross-calibration over course of experiment - Saclay/CMU DAQ cross-checks for each beam configuration - Compton history plots for each beam configuration