Neutron distribution on the face of a lot bigger ND input into MCEEP (Large ND). The black rectangular outline denotes the real dimensions and position of the ND. The plots have been resized to match the x and y axes scales. Note that the neutrons here are the ones detected along with the electrons in the BigBite (box) explaining the concentration of events within the real ND box. Here's the one from the proposal for comparison. Note that the ND here is smaller than the real one. Note also - from the proposal - "it was optimized to
have the best efficiency for a neutron momentum of 2.58 GeV/c and a threshold of 150 MeV." (Hover the mouse pointer over the gray area to see the image - visible only in standards compatible browsers; do not use Internet Explorer.)
Following is the plot of the ND xy-distribution with independent cuts on the horizontal and vertical ND dimension while keeping the Pmperp cut the same (Pmperp < 150. MeV/c). Note that 0.05 rad corresponds to about 0.45m at the ND front face. In the plot, |φ - 0.6238| < Δφ; |θ| < Δθ (numbers from Tim's document). For the real ND, Δφ = 0.2301; Δθ = 0.3329.
This plot is the same as above but with sizes relative to the real ND dimensions. Fraction of events accepted by our ND ⇒ ~87.5% on both axes.
Perpendicular missing momentum distribution from nitrogen reference data (run # 4585) and oxygen from MCEEP (1p½ nuclear shell configuration). Oxygen was used since there is no nitrogen in MCEEP (that I could find) and oxygen is the closest to it in A and Z.
This is again a plot with radiative tails - one-photon and multi-photon corrections for the neutron..
Same as above for the protons.
Using MASCARAD, internal radiative corrections on the electron side come out to ···. I am yet to talk to Andrei about this and verify my calculations. This is for kin4. Have some unverified numbers for the hadron internal rad. corr. too. These are corrections to the cross-section (the δ in σrad = (1+δ)·σno-rad). Next up, corrections to the transverse asymmetry.
August 08, 2007
Comparison between data and MC for the proton from the helion (3He nucleus). This plot shows the angle between the q and the outgoing hadron on an event-by-event basis.
Proton perpendicular missing momenta in data (left) and MC (right)for REAL ND. (The spike spoils the MC a bit.)
Neutron and proton θpq using the Meier-Hajduk 2-body break-up functions.
Neutron and proton final momenta for the Meier-Hajduk 2-body break-up functions.
Comparison between INFINITE ND and REAL ND in MCEEP. Next up is to reduce the ND from infinite size (acceptance) in small steps to determine at what point we start losing events (We are studying the ND acceptance in phase space i.e. trying to find out the distribution and cut-off of the initial nucleon momenta that will be accepted by the ND (or, equivalently, lie within its coordinate boundaries)). For, 3He the Fermi Gas model (FGM) does not work so well. The average momenta seem to be around 220 MV/c for neutrons and 260-270 MeV/c for protons (from FGM). Also, the q-angle is not a constant w.r.t. the beamline (or Hall coordinate system), but has a spread. So these plots are on an even-by-event basis.
Will have numbers for radiative corrections from simulations at the next meeting.
July 25, 2007
Difference between MCEEP 2-body and 3-body break-ups. The Continuum state is used instead of the Bound State. The 3-body does not look right - even with the other variables. The culprit most certainly seems to be the weigting factor, unless I'm making a mistake in choosing it.
Continuum state angle, neutron momentum and missing energy:
This one is the 2-body break-up. This looks good - a lot better than the 3-body one! (red is the MCEEP; black is the data. How about detector resolutions in the real data? The MCEEP does not have both our detectors in there!
MCEEP does not currently do radiative corrections for neutral ejectiles, so no radiative effects studies for our reaction can be done via MCEEP.
July 11, 2007
Mostly doing MCEEP stuff. I was thus far using 2-body break-up for (e,e'n) from 3He which is not correct. I have now started using the 3-body break-up functions. (Using the Meier-Hajduk 3-body break-up (NNN) potential)
Next, I'm looking into radiative corrections - mostly internal, including multi-photon - also through MCEEP.
June 27, 2007
Currently trying to get neutron detector calibration for kin2b. under way. (Thanks a lot to Tim for his scripts.)
Below are plots of ∠θ between the outgoing hadron and the q-vector. The first plot is from the Monte Carlo and the second one from real data. The real-data θ is calculated from the perp and the parallel components of the hadron momentum. No raster in the MCEEP. Various NN potentials give similar results.
Other variables from 3He neutrons. All momenta are in MeV/c, energies/masses in MeV, angles in rad.
June 13, 2007
:: Work in Progress ::
Some Monte Carlo results. I reduced the spatial acceptance of the Neutron Detector (Next shall look at the Pmperp and Pmpar distributions and cuts). In all of the under, I have used the Meier-Hajduk NN (2-body break-up) potential for the 3He momentum distributions.
ND acceptance 225mr horizontal and 625mr vertical (with respect to Hall floor). [SUM file]
ND acceptance 100mr horizontal and 400mr vertical (with respect to Hall floor). [SUM file]
May 16, 2007
Stuff here is just a prelim. look before the Collab. Meet. on the 16th.
Here's a plot of the target polarization with error bars. The EPS file looks a lot better.
The plot below is and expanded range from the plot above and also shown is the accumulated charge per run. The range of runs covered is the 4th kinematic. Note that no correlation between Q and pol. has been depicted in the plot. (Normalization etc.) Again, the EPS file looks a lot better
May 09, 2007
Here are some BB Scint. calibration plots for kin3 (k3) and kin2b (k2r2) The two plots below are the peak positions of two avg.-time alignment of adjacent paddles..
This one is with the db optimized for run 3369 of k3. We see that 3369 looks good, but others in the same kin., 4364 and 3365 do not. Two iterations were done on this db (with the same run 3369).
This one is with the db optimized for run 4116 of k2r2. We see that 4116 looks good, 4118 from kin.2 looks fine and from k3, 3369 has one bad point, 4364 looks good too (compared to the one bad point in 3369; the other points in 3369 are comparable to other runs)! One iteration was done on this db.
The two plots below are the same as above for the resolutions. The calibration procedure is outlined in the box below the plots.
Same as above subpoint 1, but for the resolutions. i.e. db calibrated with two iterations on run # 3369 of kin3.
Same as subpoint 2 above for resolutions. db calibrated with one iteration on run # 4116 of kin2b.
Procedure: First, all the left PMTs are aligned. This is done by plotting the difference of the left PMT corrected times for adjacent paddles, and changing the TDC time offsets in the BB Scint. database (db_B.s.dat). Then the right PMTs are aligned similarly. The run is replayed again with this new database and then alignment is checked again. This is repeated if necessary. For these alignments, paddle # 6 (i.e. the seventh - middle - paddle) is taken as the reference.
Once the left and right are independently aligned, the difference between the left and right averaged time ((L+R)/2, or the B.s.time variable) is plotted, and so is the left and right difference (L-R, or the y-position) for adjacent paddles. Note that this does not necessarily align the time differences to zero, but some arbitrary value (which can be made zero if required). The B.s.time can be further aligned by changing the L and R PMT TDCs such that the y-position alignment remains the same. This too was done for the above calibration.
It is seen that more iterations better the alignment for one particular run but can spoil it for other runs (as seen in the examples above; a likely binning artifact). So a value of ±50ps seems to work for all runs tested.
Target polarization data for each run is now available. I haven't put it in the MySQL database yet. I'll make an entry on the wiki with the data files and plots, and the scripts that generated them. This is for target cell Edna which covers kin3, kin4 and kin2b. Here is the plot:
Note that this figure does not contain all of Edna data but only for those runs that exist in the "general" table of the MySQL database.
ND "mis-pointing": For kin4, the ND (mis-)points about 173.4cm upstream of the target center as calculated from the survey data. There seems to be slight confusion as to what point on the ND the distance is quoted; so this would bring about some more uncertainty in the (mis-)pointing position along the beamline.
Target center position, T ≡ T(0,0,0);
N.D. Pointing position, P ≡ P(0,0,-173.4cm).
This information is used in the MCEEP detector-acceptance-as-a-function-of-perpendicular-nucleon-momentum studies.
MCEEP - Currently have plots to compare elastic hydrogen data with helium-3 data using wavefunction from the Argonne NN potential. Also trying other wavefunctions - most of them give similar results. Haven't yet cut on Pperp yet.
April 25, 2007
As of this moment, I have a few projects running in parallel and are, thus, in progress. The list follows ...
Having fun with asymmetry calculations for kin.4. Currently dealing with backgrounds and proton dilution.
Currently using Rob's numbers and trying to get those myself.
Obtained background asymmetries for the bg and charged particles but no ratios yet (cf. Rob's Mar 13 collab. meet talk)
Subtracting out all false numbers from the total neutral yields (the N+ etc.), and then the usual method of dividing by dil/pol factors, solving poly. eqn. and getting GEn.
Monte Carlo to model Fermi momentum dependence of our detected particles is under way.
Using MCEEP - has built in Fermi distribution ...
Currently, using protons to look at a "generic" detector response, and then modify the input to use neutrons from a 'complex' nucleus - like 3He and nitrogen.
Trying to put in "real" values for angles, positions, etc. of the detectors.
BigBite Scintillator database for kinematic 3 is ready. Am checking it with various runs now.
BB Scint. db is also ready for kinematic 2, run 2. I mention this separately because the database is a little different from the kin3 one.
MySQL database target table upgrade is also under way.
Documentation of everything I'm doing ...
April 11, 2007
The Edna polarization numbers are on the MySQL database (Thanks, Brandon). The description is detailed on the Wiki under Target and also a separate article with an obvious title.
Nitrogen dilution analysis details and useful scripts have been put up on the Wiki as well, in the Target section. There are no density data in the database yet - that's my goal for the coming week - but anyone can use the scripts to get the densities for a particular run. (If things seem off anywhere - maybe due to bad RTD readout, etc. - please let me know, though I hope to catch all discrepancies when I create the densities database!)
New and improved BB scintillator database for kinematic 3.
For one-track corrections for the N2 dilution, am considering only the accepted/good events. The dil. factor remains mostly the same.
March 28, 2007
Further analysis of LiveTimes, one-track-corrections, detector efficiencies in progress for the nitrogen dilution analysis. This is being done to complete the analysis thoroughly and know all the systematic effects well. The values remain almost the same with LiveTime corrections, though ...
... LiveTime analysis is work in progress; will use Rob's GenNormAna class to get correlation of the T7's with beam current. Here are my values for a typical production run (kin4 run 4545):
Electronice LiveTime: 89%
DAQ LiveTime: 77%
Total LiveTime: 68.5%
Rob's plot is at the end of the page here. Below are plots of the LiveTime calculations for run # 4530:
Luminosity/rates dependence of the efficiency of the detectors - to be investigated.
Number of tracks considered during N2 runs and production runs. Plot showing tracks skipped during BB tracking for prod. run # 4530 is shown below:
For example, for production run 4545, 49.8% single-track events are "good events", and 13.32% one-track events are skipped. For nitrogen run 4585, the numbers are 54.24% and 12.34% respectively. This is only for the BigBite, still to figure it out for the ND.
BB Scint. timing resolution looks good for kinematic 3. The alignment can be improved a little, and am working on that. Below is the plot for all the bars for run 3356. Again, since each point represents difference between two bars, the individual resolutions are a factor of √2 better!
Should start replaying some kin2 hydrogen/nitrogen runs for my own point.
Should have a 4th kin. GEn number *soon*!
Am calculating compass magnet self-effects using magnetostatics - in progress.
MC for nucleon momentum distribution effects being discussed with Wolfgang.
March 13, 2007
Dilution factor (for run # 4545; nitrogen ref. run # 4585) as a function of Pmperp (cont'd from last week):
|Pmperp| < 0.25, D = 0.9543 ± 0.0119
|Pmperp| < 0.15, D = 0.9539 ± 0.0122
|Pmperp| < 0.10, D = 0.9536 ± 0.0127
|Pmperp| < 0.05, D = 0.9541 ± 0.0152
|Pmperp| < 0.03, D = 0.9551 ± 0.0173
The errors are purely statistical (from the number of events after all cuts are applied). These also do not have Pmpar or W cuts.
D with Pmperp, Pmpar and W cuts as follows:
|Pmperp| < 0.25, |Pmpar| < 0.25, 0.8 < W < 1.15, D = 0.9529 ± 0.035
|Pmperp| < 0.15, |Pmpar| < 0.25, 0.8 < W < 1.15, D = 0.9528 ± 0.035
March 07, 2007
Dilution factor as a function of Pmperp:
|Pmperp| < 0.25, D = 0.95425
|Pmperp| < 0.15, D = 0.93157 (⇐ Mistake!! See Mar 13 above.)
|Pmperp| < 0.10, D = in progress (NEW after meeting: See March 13 above.)
Have enough runs analyzed in kin.3 to start checking the BB Scint. Timing Calibration.
Otherwise working on kin.4.
...
Here is a script to get the 3He and nitrogen densities from the production cell's target chamber: Production Cell Density Script. And here's one to get the densities (currently at 135psig) of a reference cell gas at 135psig. This can be modified if required to incorporate any pressure. Ref cell density Script. I'll soon put a table in the MySQL database and on the wiki. These codes will also go on the wiki.
Here is a script that converts the date and time for Edna polarization into linear plottable format. These are the datafiles before and after running the script: edna_all_poldat.dat; edna_lin_time_pol.dat.
February 21, 2007
Nitrogen dilution factor, D, for a few runs is at the end of the dilution page.
Looking into how different momentum cuts (Pperp, etc.) affects the N₂ dilution factor.
The automated script to get the resolutions of the BB Scint. detectors now works in batch mode also - inputs are the start and end runs. This still has a bug - it only works for successive runs. Will try to fix this.
Took a first look at the BB Scint. calibrations for kinematic 3 runs that have been analyzed. Not nearly enough statistics!
A nitrogen dilution automation script is complete. It's still in the semi-automatic phase since scaler information needs to be input. This script takes all temperatures from the RTD EPICS variables from the MySQL database and averages them over the run period. This does not yet incorporate possibly different RTD offsets, beam trips, etc. But I think it's better than just one reading from the start_run halog entry.
Documentation of all the above work is in progress.
Working on the asymmetry analysis for kin. 4.
Speed Determinant:Slowness Factor: None that I could think of. I'll get the target logbook copies when Chiranjib (another Wolfgang's student) comes over to Ky end of Feb. And the D analysis is separate from A analysis (kin. 4). Otherwise, as soon as some kin. 3 runs are analysed, I can check the BB Scint. Calibration. I think there's enough documentation to begin work.
February 07, 2007
Nitrogen dilution factor, D, for run # 4590 is around 0.94 ± 0.0193syst ± 0.011stat. The errors are conservative estimates, assuming individual errors slightly higher than actual.
Looking into the asymmetry analysis of kin.4
Improved the automated script to get the resolutions of the BB Scint. detectors - shall put it on the wiki soon.
January 24, 2007
All progress in pulsed beam and nitrogen dilution pages ...
January 10, 2007
Made some progress on the pulsed beam hydrogen analysis. See pulsed page.
On track to get nitrogen dilution factor. A crude first number is almost ready but for the nitrogen density information for Edna just got it from Al Tobias. (Run#4583 which is noted as reference nitrogen at 10psig is apparently only air - i.e. vented reference cell).
Shall work on glass dilution factor after this.
Going through the "bit more involved" QE.C and QE.h but I guess quasi_elestic.C would be more useful for now for N2 dilution analysis.
December 13, 2006
As per Bogdan's request, here's one plot of the BB trigger - This is important because currently the MWDC's get their time relative to the BB trigger, and shifts in the trigger time at the 10ns level can make a difference in the evaluation of the
drift-distance. We expect the width of these peaks to be <50ns or equivalently, σ<21.24ns. This one is for the pulsed beam hydrogen run # 4223. And the one below is the same as above over the entire range.
This plot is the BBTrig Time for production run # 4545. Only ~100K events were analyzed for this specific.
November 29, 2006
Made some progress in understanding Rob's asymmetry script
Further tuned the BB scintillator database
Pulsed Beam Analysis in progress - see link at the top of this page.
Nitrogen dilution next
November 08, 2006
Looking at timing calibration (BB Scint. + RF etc.) for the 3rd kinematic point to make sure it still works fine. It was fine the last time I checked. Will do some more fine-tuning.
Going through Rob's procedure for getting asymmetries for the 4th kinematic - trying to understand things!!
Should get a good number for the nitrogen dilution factor once i can get the neutrons in.
Compass measurements and pictures/images are now in a dedicated folder - here. And I'll also setup a directory on the workdisk.
Ameya Kolarkar
Last modified: Wed Sep 5 15:33:10 EDT 2007
's the one from the proposal for comparison. Note that the ND here is smaller than the real one. Note also - from the proposal - "it was optimized to
have the best efficiency for a neutron momentum of 2.58 GeV/c and a threshold of 150 MeV." (Hover the mouse pointer over the gray area to see the image - visible only in standards compatible browsers; do not use Internet Explorer.)
