Project

General

Profile

Kaon LT Meetings » mtg_24apr11.txt

Garth Huber, 04/11/2024 06:43 PM

 
1
                 Apr 11/24 PionLT/KaonLT Analysis Meeting Notes
2
                 ----------------------------------------------
3
                                (Notes by GH)
4

    
5
                     Today: KaonLT will be discussed first
6

    
7
Please remember to post your slides at:
8
https://redmine.jlab.org/projects/kltexp/wiki/Kaon_LT_Meetings
9

    
10
Present
11
-------
12
Regina - Garth Huber, Nathan Heinrich, Muhammad Junaid, Alicia Postuma,
13
   Nacer Hamdi, Ali Usman, Vijay Kumar
14
CSULA - Konrad Aniol
15
York - Stephen Kay
16
UVa - Richard Trotta
17
JLab - Dave Gaskell
18
CUA - Tanja Horn
19
FIU - Pete Markowitz
20

    
21
Richard
22
-------
23
Resolving various issues in KaonLT LT-separation
24
- RF time cut now removed
25

    
26
- -t distribution offset between data and SIMC
27
  - found that proton mass was used for detected particle instead of K+
28

    
29
- SIMC recon script did not use the updated kinematics to recalculate the
30
  weight
31
  wt'= wt*(sig/sigcm_sim)
32

    
33
- weights were not properly recalculated when doing an iteration
34
  - ROOT was always using the first iteration weights
35
  - an over-writing issue in ROOT script now fixed
36

    
37
- with these corrections, there is a significant improvement in the
38
  phi-distributions at high and low epsilon for the kinematic setting shown,
39
  Q2=3.0, W=3.14
40

    
41
Outstanding issues
42
- some mismatches remain between SIMC and data distributions
43
  - PMISS shape is off
44
  - Dave: this could be due to the SIMC model not yet being optimized, wait for
45
    more iterations to be completed before checking this again
46

    
47
- pion subtraction needs improvement
48
  - "clean" pion sample used for Q2=3.0, W=3.14 leakage subtraction clearly
49
    shows some K+Lambda events
50
  - Garth: need to be very careful with the pion subtraction, as it has a
51
    different epsilon-dependence than the true K+ events, and you don't want to
52
    induce an artificial epsilon-dependence to the data
53
    - also very important that both K+ and pi+ samples populate the same focal
54
      plane limits, i.e. can't have an HGC hole cut on one but not the other
55

    
56
Vijay
57
-----
58
Low Q2 pi+ LT-sep update
59
- unseparated cross sections shown for 3 epsilons
60
  - some weird issues remain with phi-distribution of lowest -t bin, although
61
    not as bad as last time this was shown
62
- preliminary separated cross sections for L,T
63

    
64
- no ratios or kinematic comparison plots shown, so it's impossible to provide
65
  helpful suggestion on what to look at
66
  - it's *VERY IMPORTANT* to also show diagnostic plots
67

    
68
Ali
69
---
70
piDelta BSA analysis
71
- last week, showed some preliminary BSA results at Q2=3.0, W=3.14
72
- since then, the t-bin limits have changed
73
  - the issue is that the background in the Delta region grows immensely with
74
    -t
75
- HGC cuts are applied to remove K+Lambda contamination in piDelta region
76
  - *IMPORTANT* any SIMC plots need to have the same cut
77

    
78
- MM plots shown for new -t bins, 0-0.37, 0.37-0.60, 0.60-1.0 and total 0-1.0 
79
  - will exclude the 0.60-1.0 region since there are too few piDelta events
80
    there for a reliable fit
81
  - in process of doing MM fits for new t-bins
82

    
83
  - an issue with 0.37-0.60 region is that some phi bins (center setting) have
84
    very strong background, so getting a good piDelta fit is tricky
85
    - the SIDIS background grows much faster with -t than the piDelta does
86

    
87
Alicia
88
------
89
pi+n BSA Q2-scan
90
- delta(FIT) error will be treated separately from delta(CUTS) error, since
91
  they're not of comparable size
92
  - doing RMS of both together results in under-estimate of total uncertainties
93

    
94
- LT'/sig0 data shown vs. Regge model curves from B-G Yu
95
  - much larger x-dependence than Q2-dependence
96
  - LT' at fixed t vs Q2 is mostly flat, but different for each x-bin
97

    
98
- overlay of LT' at xB=0.25, 0.40
99
  - xB=0.25 data sets at Q2=3.0,W=3.14 and Q2=2.1,W=2.95 overlap very well
100
  - xB=0.40 overlay has more scatter, but still small Q2 dependence
101
  - Dave: how different are the -t_min for the two xB=0.25 data sets?
102
    - the difference is quite small, about 0.01
103

    
104
  - Dave: since the Q2-dep is small, how about overlaying all Q2 and look at
105
    the x-dependence
106
    - Alicia will make a plot for next week
107

    
108
Nacer
109
-----
110
Low Q2 K+ PID studies
111
- using runs=6921-6978, Q2=0.5, TH_shms=9.79(left) for comparison
112
- Main cuts:
113
  - H.cal.eTotTrackNorm>0.5
114
  - H.cer.npeSum>2.0
115
  - 0.15>RFtime(corrected)>0.95
116

    
117
- RF time correction
118
  - applied an adhoc correction to remove xptar dependence
119

    
120
- Signal/Bkd study via a Gaussian fit + polynomial bkd
121
  - does fit vs RF time cut
122
  - apply both Low and High RF cuts, vary each one independently
123
  - optimum values: Low=0.15, High=0.95
124
    - throw away events between these limits, correponding to pions
125

    
126
- Best K+Lambda yield appears to be with only RF cut, RF+HMS cuts is similar
127
  - applying SHMS cuts greatly reduce the K+Lambda yield due to various
128
    inefficiencies, the extra clean-up of the MM spectrum is not worth it
129

    
130
  - Ali: there appears to be a small amount of piDelta contamination underneath
131
    the K+Sigma events
132
    - suggests to do a pi+ leakage subtraction, similar to what Richard is dong
133
    - Garth: since the RFtime is so effective, can use a tight RF cut to easily
134
      generate a clean pi+ spectrum for subtraction
135

    
136
- Next steps
137
  - RF cut efficiency, Lumi checks
138

    
139
Nathan
140
------
141
PionLT lumi scans
142
- figured out a reasonable BCM offset for the runs in this scan
143
  - offset=-0.17uA
144
  - make scaler(ELREAL) normalized yield flat vs rate
145

    
146
- RelYield-NoTrack has a rate dependence (anti-boiling) indicating a LiveTime
147
  issue
148
  - TotalLiveTime(TLT) is too low at high rate
149
  - Dave: as an intermediate step, try using CPULT instead of TLT, the
150
    Electronic DeadTime should be very small
151
  - Richard: can use the CPULT to fine tune your cuts, then re-introduce EDTM
152
  - Nathan will add EDTM timing plots to investigate cuts
153

    
154
- Dave Mack sent a new BCM calib, but had difficulty w/replay, investigating
155
  - has a meeting with DM next Monday re. learning how to do BCM calib
156
  - Dave: do we know how complicated the BCM calib is?
157
    - the UNSER is very noisy, DM throws away UNSER points that are outliers,
158
      requires some judgement
159
    - Nathan: expecting to generate plots and have DM identify outliers to be
160
      removed, will still take less time than DM having to do all parts from
161
      scratch
162

    
163
Junaid
164
------
165
- arriving at JLab on Tuesday night
166
  - Dave: beam studies on Wednesday, so a Hall C walk through is possible
167

    
168
PionLT Heep analysis
169
- Ali had pointed out that BPM calibs were wrong
170
  - slope values were right, but offsets wrong.  All updated now
171
  - raster config files were also wrong
172
  - there was an issue for two run ranges where only one pair of raster coils
173
    were operational, so the other had to be run at double current
174
    - this is also fixed
175

    
176
- Heep Effective Charge, corrected for TrkEff, but not Calor or Cer Eff
177
  - wrong BCM still used
178
  - for setting shown, the data normalized yield is ~2x SIMC yield, which is
179
    surprising
180
  - for a different run, the yield ratio is much closer to 1
181

    
182
- Richard: you need to use the kinematics recon script on SIMC data
183
  - unfortunately, this means the PM, etc. plots have to be redone again
184

    
185
- Dave: make sure you have the correct_eloss flag turned off in the SIMC input
186
  file
187
  - by default, SIMC both does energy loss, and corrects for it in the event
188
    reconstruction, but hcana does not correct for eloss, so you need to turn
189
    it off
190

    
191
Next Meeting
192
------------
193
- Thur April 18 @ 15:00 Eastern/13:00 Regina
194
  - PionLT will go first
195

    
196

    
197

    
198
   
199

    
200

    
201

    
202

    
203

    
204

    
205

    
206

    
207

    
(412-412/564)