Project

General

Profile

Kaon LT Meetings » results_summary_23aug28.txt

Garth Huber, 09/01/2023 01:33 PM

 
1
Hi again,
2

    
3
PeterB agreed with the idea of repeating the fit with a constraint on the beam
4
energy offset based on the arc energy measurement uncertainty.  The new results
5
are below.
6

    
7
According to the log, each measurement has an uncertainty of about 2.6 MeV,
8
independent of energy at least for the range 2.7-4.9 GeV.  That corresponds to
9
a fractional uncertainty of 0.59-0.87E-3, so I took +/-0.7E-3 as the constraint
10
on the beam energy offset dE.
11

    
12
However, one of the measurements, had a significant issue in that the arc
13
energy tool gave an energy of 2.7832 GeV, which was surprisingly far from the
14
expected 2.75 GeV.  After some discussion in June-2019, MarkJ came up with a
15
revised estimate of 2.74996 GeV, which I think Vijay is using his analysis.  So
16
I'll assume the uncertainty on this measurement is the same as the others for
17
now, but this might need revisting.
18

    
19
I also fixed an error, which was that the Heepcheck derivatives were calculated
20
for a wrong setting for one of the energies.
21

    
22
With this beam energy offset constraint, the global fit offset results look
23
quite a bit more reasonable.  As expected, the dpp(SHMS) and dpe(HMS) offsets
24
are also now quite a bit smaller.  The dthp(SHMS) angle offset is also quite a
25
bit smaller, while the dthe(HMS) angle offset has grown slightly.
26

    
27
Finally, the chi-square per energy is also more uniform.  The 3.6 GeV Heep
28
setting still has the largest chi-square contribution to the global fit, but by
29
a lesser amount than before.  Of course, the overall chi-square is slightly
30
larger now, as the constrained fit no longer corresponds to the absolutely best
31
fit, but the difference is not huge.
32

    
33
If you have questions or comments, please let me know.  We can discuss these
34
further at Thursday's meeting.
35

    
36
Thanks, Garth
37

    
38

    
39
 *** RESULTS *** 
40
! units are 0.1% for momenta/energy, 1 mrad for angles
41

    
42
 Global Offsets:
43
   dthe  1.3000   dpe  0.0000   dthp  0.7000   dpp  1.8000
44
   dE: -0.7000    0.7000    0.7000    0.0000   -0.2000
45
   chisq:  48.357     5.608    17.334     9.608     5.458    10.350
46

    
47
 Offsets for Energy:   2750.0
48
   dthe  2.3000   dpe  0.0000   dthp  0.3000   dpp  4.8000   dE  0.7000  chisq   3.201
49

    
50
 Offsets for Energy:   3660.2
51
   dthe  0.4000   dpe  0.1000   dthp  0.1000   dpp  1.4000   dE  0.6000  chisq   0.082
52

    
53
 Offsets for Energy:   3834.9
54
   dthe  0.1000   dpe  0.6000   dthp  0.7000   dpp  0.0000   dE -0.1000  chisq   0.603
55

    
56
 Offsets for Energy:   4559.7
57
   dthe  0.4000   dpe  1.6000   dthp  1.8000   dpp  0.0000   dE -0.1000  chisq   2.795
58

    
59
 Offsets for Energy:   4932.0
60
   dthe  0.9000   dpe  0.8000   dthp  2.2000   dpp  0.2000   dE -0.5000  chisq   4.194
61

    
62
 *** Expected shifts *** 
63
 units are 0.1% for momenta/energy, 1 mrad for angles
64

    
65
 --- Original --- Global --- Individual Fit 
66

    
67
Energy   2750.0
68
 W    6.3945      1.2125      0.5605
69
 EM   4.0667     -0.5763     -1.2563
70
 PMZ  4.0486      1.5776      1.1436
71
 PMX -0.5784     -1.1474      0.0186
72

    
73
Energy   3660.2
74
 W    1.0657     -3.7233      0.0367
75
 EM   0.8051     -0.4669     -0.1919
76
 PMZ  0.8696      1.4406      0.2086
77
 PMX -0.8696      1.0854      0.0244
78

    
79
Energy   3834.9
80
 W    3.1973     -2.1227      0.1733
81
 EM   1.0916     -0.6014     -0.5094
82
 PMZ  1.1614      1.2994      0.5594
83
 PMX -0.3871      1.7469      0.0269
84

    
85
Energy   4559.7
86
 W   10.6576      1.8176      0.3706
87
 EM   3.3951     -1.3749     -1.1409
88
 PMZ  2.5072      0.4362      1.1642
89
 PMX -0.7163     -0.2713     -0.0173
90

    
91
Energy   4932.0
92
 W   12.7891      2.3761      0.5001
93
 EM   4.0027     -1.3573     -1.4443
94
 PMZ  2.7100      0.7800      1.3630
95
 PMX -0.7743     -1.5013     -0.0113
96

    
97
Mean  2.7718      0.0315      0.0789
98

    
(282-282/443)