Capture Alvarez searches on TDC spectra

Overview

Analysis procedure

performed at kaon tr4/test, pdsf tr4

• software
• ehsel routine developed (end of mu_histn.f), check selection there
• skimming routines developed
• event display upgraded
• analysis
• myjobskim on pdsf
• additional input para in inputs (fort.15) for write/read skim file
• iskim=1  for skimming
• iskim=2  for display (disp=1)
• updated esel parameters

*       esel(1)      # tpc (>0 turns on selection)
sel(1) determines which space to search:
• 1 = EL
• 2 = EH
• 3 = EVH (3rd threshold mode, tdc00)
*       esel(2)      z1
*       esel(3)      z2
*       esel(4)      t1
*       esel(5)      t2
*       esel(6)      required candidates
*       esel(7)      high/low ratio > esel(7) in selection box
*       esel(8)      =1, time reflect box
e.g. if region around t=0 should be excluded
 
• capture 108,109

1 100 0 0 10  1
3 -1 1 5 40 1 0 0
1
tdc00.109
zch

• Alvarez 108,109

1 100 0 0 10  1
3 1 40 -40 60 1 0 0
1
tdc00.109
zch

• capture 268,269

1 100 1 0 10  2
2 -1 1 -40 60 1 0 0
1
tdc00.268
zch

• Alvarez 268,269

1 100 1 0 10  1
2 1 40 -40 60 1 0 0
1
tdc00.268
zch

Alternatively, Alvarez mu's were also searched with
• Alvarez 108,109

1 100 0 0 10  1
2 1 40 -40 60 8 35 0
1
tdc00.109
zch
requiring  8-10 EH in search rectangle and 0.35 EH/EL ratio

Preliminary results

 

run		mvg/event	capture/ev	Alv/ev	long EVH/ev
108	+	350	1/100=0.01	1/1800=5.5e-4	0
109	-	390	20/40=0.5	15/1800=8e-3	8e-3
268	-	430	16/10=1.6	0	0.067
269	+	380	0	0	0

Discussion:

• expected Alvarez yield= 3e-4 x 0.5 x eps =1.5e-4 eps
• observed Alvarez yield= 8e-3 /390 = 2.0 e-5

eps=0.1, obvious loss factors: out diffusion, close production, but still eps rather low.
I also checked long mu track versus EVH selection, EVH seems more efficient, but
threshold not really calibrated. Only by looking at mun stops.

• mug rate = 390*1800/1800s= 400 Hz

obvious loss factors there:
• deadtime 0.5
• PU 0.25
• fiducial stops 0.4
• total = 0.05, i.e. total incident rate about 8 KHz, ok

• in addition run 3 (223, 224) were analyzed. No EVH, but x info. Long red tracks

clearly dominated by x edge effects, similar for mu+, mu-. Perhaps one can find
candidates by
• excluding edge effects
• origin of second muon separated from stop anode
Nedds further software work.

Conclusions

• 3rd threshold required
• capture diagnostics extremely powerful: clean and good statistics. 0.01 ppm level reasonable.
• Alvarez diagnostics much harder:
• presently 30/hour. Better detector and analysis should give order of magnitude more, i.e.

2/hour at 1 ppm level.
• Discrimination to mu+ unclear. At the moment around 5% level. Hopefully x helps a lot.

Timing signal with chamber, full energy signal with scintillator??
• Efficiency low. Do I miss signals. FADC comparison.