Log entry time 04:46:54 on October28,2005

Entry number 158255

keyword=P0 scan on R-arm

Run 2912 was a Q² run at 0.2 uA

Now, we will scan P0 (and septum) on Right HRS only.
Purpose is to see how ratio of rates between detectors change.

Spectr. DAQ run ..... P0 ....... I_sept (set pt)

2913 ...... -3 MeV .. 3109.6 MeV ... 316.6 Amps

Decide to run at 0.6 uA. This way we have stripline info
and some hope of feedback.

2914 ... junk, wrong PS factors
2915 ...... -3 MeV ... 3109.6 ... 316.6 (repeat run 2913 at 0.6 uA)

2916 ...... +2 MeV ... 3114.6 ... 317.1

2917 ...... +4 MeV ... 3116.6 ... 317.3

2918 ...... +6 MeV ... 3118.6 ... 317.5

Between run 2918 and 2919 we lost L-arm IOC. hareboot10.
2919 ...... +8 MeV ... 3120.6 ... 317.7 ... (L-arm recovery)

2920 ..... +10 MeV ... 3122.6 ... 317.9

At 02:55 we switched back to HAPPEX DAQ.
Did the checklist. HAPPEX run 5942. Note, the beam started
at 0.6 uA then was slowly ramped up to 58 uA during run 5942.

HAPPEX Run .... P0 ...... I_sept

5942 ..... +10 MeV ... 3122.6 ... 317.9 ... (L-arm still recovering)

Noticed online that det4 is at 60K (det3 at 25K). Decide to
reduce the beam current a bit (to 50 uA).

5943 .... +10 MeV .... 3122.6 ... 317.9 .. repeat with 50 uA

5944 .... +8 MeV ..... 3120.6 ... 317.7

03:40 This procedure is slow ! Decide to skip a few points.
5945 .... +4 MeV ..... 3116.6 ....317.3

Note, beam is really unstable (lots of RF trips).

5946 .... "0" MeV .... 3112.6 .... 316.92 ... normal conditions
except this will be a short run at 50 uA (don't change too
many things).

Next, start a normal production run 5947 with 58 uA.

Here are some numerical results, to be plotted later.

Spectr. DAQ runs results
Always, a cut on bcm is made (define beam on).
Ratio of detectors to bcm are considered, though bcm drops
out in ratio of det1 to det2 below. T2 is overall trigger rate
and is normalized to bcm (u10).

P0 .... det1/u10 .... det2/u10 ... det2/det1 ... T2/u10
-3 MeV ... 14.6 ...... 25.5 ....... 1.75 ....... 38.8
0 MeV ... 16.0 ...... 21.9 ....... 1.37 ....... 37.5 .. run 2912, at 0.2 uA
+2 MeV ... 17.9 ...... 21.1 ....... 1.18 ....... 37.9
+4 MeV ... 19.3 ...... 19.2 ....... 0.99 ....... 37.5
+6 MeV ... 20.9 ...... 17.0 ....... 0.81 ....... 36.9
+8 MeV ... 22.0 ...... 15.2 ....... 0.69 ....... 36.3
+10 MeV .. 23.4 ...... 13.0 ....... 0.56 ....... 35.6

So, going from nominal P0 to +10 MeV the ratio det2/det1
decreased by 60% and the T2 rate decreased by 5 to 7% (range
is a syst. error because of different beam currents).

HAPPEX DAQ results
For det/bcm ratio, bcm1 cut made. For asymmetry, "ok_cut" used.

P0 .. det3/bcm1 .. RMS Asy .. det4/bcm1 .. RMS Asy .. width ratio(*)
................... det3 ................ det4 ...... ~ det3/det4
+10 MeV .. 1.43 .. 1377 ...... 3.42 ..... 1039 ..... 0.57
+8 MeV ... 1.66 .. 1279 ...... 3.22 ..... 1081 ..... 0.71
+4 MeV ... 2.10 .. 1131 ...... 2.81 ..... 1133 ..... 1.0
0 MeV ... 2.51 .. 1052 ...... 2.39 ..... 1240 ..... 1.39

(*) width ratio = (RMS-det4)^2 / (RMS-det3)^2 which is
nominally N_3/N_4 (ratio of rates). It's presum. less reliable to
use det*/bcm because of arb. PMT gains, however the trend in
the detector ratios are roughly consistent with "width ratios".

So, going from nominal P0 to +10 MeV the ratio det3/det4 from
the "width ratios" decreases by 60% (consistent with counting
mode result) and the overall rate judged from quad. sum of
widths decreases by 11%, roughly consistent with cnt mode.
Here, its assumed the overall rate is proportional to
1 / ( (RMS-det3)^2 + (RMS-det4)^2 )
(Indeed, there is a slight optimum around +4 MeV in this "rate").

Plots coming ...

And it looks like the mapping of detector numbering is
Spectr. DAQ .... HAPPEX DAQ
... det1 ....... det4
... det2 ....... det3

User name R. Michaels

Log entry time 04:46:54 on October28,2005

Entry number 158255