BT Meeting, 6 september 2007, Notes
Unedited notes taken during the meeting, comments and additions are welcome LL
Participants: Luca Latronico (LL), Leon S Rochester (LSR), Benoit Lott (BL), Takkaki Tanaka (TT), Markus Ackermann (MA), Philippe Bruel (PB), Hiro Tajima (HT), Michael Kuss (MK), Jan Conrad (JC), Tomi Ylinen (TY), Elliott Bloom (EB), Berrie Giebels (BG), Eduardo do Couto e Silva (EDC), Gary Godfrey (GG), Ping Wang (PW), Bill Atwood (BA), MarioNicola Mazziotta (MNM), Piergiorgio Fusco (PF)
News
- Updated BT deliverables list
LL: presented this to the IFC on monday that well received it and was impressed by the team work. It is a useful guide for us too in order to have future spelled out - BTRelease status - Michael Kuss
Old sims from Francesco harder to compare as not run on boer. New BTRElease running a factor 3 slower, 5 times more memory, but we can live with that on the pipeline. We will keep on looking for the memory leak, but in the meantime the plan is to start generating full statistics runs.
LL: next run to generate is the special run with modified TKR geometry with a vacuum layer between the SSD and the tray facesheet to test secondary delta rays propagation
CAL Calibration issues - Elliott
This is work done by Ping and myself, she is trying to calculate de/dx code and comparing to geant.
3: Weaver-Westphal (WW) is probably best code for de/dx available, talked to Weaver few times as he is in LBL. here are some results from his code
4: fred piron et al wrote a note some time ago comparing G4 with other MC and PDG and Bethe-Block (BB). he found that g4 values did not agree very well with calculations. there are in fact some differences in what is calculated: the mean energy deposit is calculated, in the case of geant, while what is calculated in WW, PDG and BB is the energy loss, expected to be higher. nevertheless there seem to be issues from geant.
5: very good agreement between ground data and MC for LAT for CAL_MIP_Ratio
6: the factor used for calculating CAL_MIP_Ratio seem to be there to match data and MC; in fact the 15% difference is wrt WW, which is energy loss (higher) and not deposition (lower)
7: ping figured this out (cuts and geometry) with help from leon and tracy, now we have another person able to do this
LSR: 20.2 is probably mm, not cm (typo)
EB: yes, got it from an email, you provided that so
LSR: number is right, if you got it from the code, units might not be
PB (from message board): it is not a typo : center of tower 10 : 374.5/2+27.84/2 = 201.17mm
8: energy deposition and energy loss plots for a 1GeV muon
9: same plot as 4 with direct CAL-only gleam simulation for energy loss added. again some issues with calculated values
10: conclusions
LL: it seems to me that the only issue is with different versions of g4 (g4v6 vs g3 and g4v5 as in slide 9 and 4) as the difference wrt calculated values is explained by the difference between energy loss and energy deposition. Did you also say that error bars are smaller than they should?
EB: error bars are correct, but all data points look different, and the most different is the last one
BL: the note was not written by piron, but by thierry reposour, you might want to aknowledge the right person. the purpose was more focused on comparison on predictions for carbon. the CsI slab thickness that was used by thierry was very thin (1mm i recall). the contribution of deposition is fairly low, as many e actually escape the slab, go out and do not release energy therein. so there is good reason for a higher energy deposition that you find for a much thicker (1.85cm) slab as you have used here
LL: which version are we using in BTRelease or GlastRelease?
LSR: v8
LL, PB: yes
EB: we are using g4v6r29p5
MK: well numbers can be different, v6r29p5 is our numbering convention related to our g4 external library version, nothing to do with actual g4 version
EB: how do we find corresponding version?
LSR: probably picking g4v8
HT:very basic question - when you say mean de/dx do you mean peak or average value from the distribution?
EB: slide 8, both calculated, we compare the same quantities in every case
HT: when you calculate mean energy loss, do you include all energy band, i.e. not just what is in the histogram which may be cut?
EB: all you see is on the plot and there are no other data points
BA: wrt calculation of CalMipRatio, since the code is ultimately from me, the energy factor was simply determined to make the peak with muon runs to make 1. nothing fancy there. calcsirln is derived by tracing tracks to the cal and making equivalent rl path
EB: thanks, very useful
Need to edit notes below still LL
GSI analysis - Eduardo
preliminary work, got some feedback from eric g which i could not include as i was away
2: motivation: getting ready for leo and have limited tests for timing for cal triggers
gsi data are natural place to look at. hope this analysis will evolve into LEO analysis. hoèe to extend to other ion
specieds
3: so far 1 run only.
4: basic distributions, no cuts, will make simpe selections. will look at highest trigger types (22 and 30)
5: middle plot is maxene in cal, bottom plot is the question, i.e. difference of cal-lo - cal-hi. expected to be
negavitve, cal le cannot arrive before cal he
PB: blue is 22 (cal he on), red is 30 (cal he off) do not understand middle plot
EDC: max energy in a crystal when the cal
BL: seems that blue and red are swapped
EDC: could be, will check offline
6: time arrival difference for different gem cuts
7: first column, middle row, condarrival toime for cal-lo, bottom row for cal-hi. second col,
8: same color code, top row is the same as from slide 7
EB: what do you know above a priori timing between those guys
EDC: inferring they are not different, but we do not, will comment later
8: time by multiply a tick by 50 nsec
9: shoulder at 5-10 ticks, from diode en depositiojh, ususayl 5-10 ticks earleir than peak deposit. these are expected.
we did this with cal-lo during IT, not with cal-hi as we had no events.
10: test this idea by looking at neighboring xtals
11: twr 1 triggers, twr2 triggers. please note once again the difference in x and y axis. point is that there is abunh of
evts taht
12: same for cal-le
13: trying to point out what these events are from slide 7
15: could it be the jitter (slide 9)? a jitter would be between 2 and 4 ticks, but it extends up to 10-12 ticks, so must
be something else
eric argues that cal-lo should never be allowed to open the trg ewindoew ...
LSR: could it be a skewing effect?
EDC: will check that, will talk offline.
LL: look for clean evts, instantenous rate is much higher wrt avereage
BL: avg non-interacting energy deposit is below cal-hi threshold. did you consider looking into cern events? we should
have more handlkes, and we have external trigger too, so potentially you could extimate timing wrt extern trigger
EDC: right, looking at cern data too, this came earlier
BA: slide 8 middle plot: the energies are all>1GeV in a xtal, nothing to do with cal-lo events
EDC: must go back to
BL: is there a schematic
BA: what is the status of understanding tkr multiplicities? variable we use tkr1corhc) very important var in bkg rej,