Project

General

Profile

Kaon LT Meetings » grp_22mar04.txt

Garth Huber, 03/14/2022 06:01 PM

 
1

    
2
		Mar 04/22 Group Meeting Notes
3
                -----------------------------
4

    
5
Participants: Garth, Stephen, Vijay, Ali, Nathan, Love
6

    
7
Vijay:
8
- good discussion on how to deal with pion leakthrough in (e,e'K+) analysis
9

    
10
Three methods come to mind:
11

    
12
1. Histogram subtraction
13

    
14
   i.e. make a clean pion sample, normalize the pi+n MM peak to the leakthrough
15
   to determine the scale factor, and subtract the clean pion sample from the
16
   K+ sample to get a clean(er) K+ sample
17

    
18
   Advantages:
19
   - accurately models the pi+Delta0 shape underneath the Lambda and Sigma
20
     peaks
21
   - once the MM scale factor is determined, in principle this can also be used
22
     to clean up focal plane and other observables, for comparison with MC.
23

    
24
   * Cautions/Suggestions for Future Work*
25
   - this method only works if the pion leakthrough fraction is same for pi+n
26
     and pi+Delta0 MM regions
27
   * Need to investigate the stability of the pi+n/pi+Delta0 ratio
28
     vs. CoinTime, RF cuts
29

    
30
2. Polynomial subtraction
31

    
32
   i.e. fit a polynomial to the clean pion MM sample, and use that polynomial
33
   (with adjustment) to get a clean K+ sample
34

    
35
   Advantages:
36
   - Vijay shows that this method seems to work for at least one setting
37

    
38
   *Cautions/Suggestions for Future Work*
39
   - need to be sure that the Lambda, Sigma radiative tails are not
40
     over-subtracted, as they are an important part of the reaction yield
41
   - if this method is used, the best way would be to get the Lambda, Sigma
42
     peak shapes from SIMC and use that, in combination with the polynomial, in
43
     the fit
44

    
45
3. Clean K+ cuts
46

    
47
   i.e. make a clean (e,e'K+) spectrum by applying tight cuts to eliminate most
48
   if not all pion leakthrough
49

    
50
   *Cautions/Suggestions for Future Work*
51
   - almost certainly, this gives a lower K+Lambda yield than methods 1,2
52
   - the lost K+Lambda events would have to be corrected for via a "cut
53
     efficiency".  It is not immediately obvious on how this efficiency factor
54
     would be determined, maybe by comparing with methods 1,2, but in that
55
     case, why not just use them for the analysis?
56
   - however, a quick comparison of the lower yield from method 3 compared to
57
     methods 1,2 could be useful for systematic error determination, for
58
     example by setting an upper bound on how large the cut-event-loss effect
59
   is
60

    
61
Vijay should keep track of this discussion, for use in his further studies
62

    
63

    
(32-32/513)