| Status |
ExpNbr |
Date |
Author |
Type |
Category |
Target-Source |
Subject |
| Fixed | e768s |
Mon Jul 22 16:54:33 2019 |
Marlène, Franck, François & Nicolas | BEAM | General | | Cheking beam transmission from G1 profiler to VAMOS |
Goal:
Estimate beam transmission from profiler to VAMOS (FP)
Method:
1. Beam intensity is reduced with the pepper pot 1/9 and by closing slits after the 15O target production and the accelerators so that the beam quality (emittance, etc...) is not affected.
2. VAMOS plate is removed to allow the direct beam detection
3. LiF (1.25 mg/cm2, number 1) is in position
Results:
1. beam intensity at G1 profiler ~ 4e4 pps
2. VAMOS FP ~ 2e4 pps
Discussion:
1. There is a factor of two loss between the profiler and VAMOS. Taken this factor into account in the g-ray yield estimate (see post ..) the numbers of 1297- and 1340-keV g-rays is in line with what is expected from cross-section calculation.
2. Loosing a factor of two means a substantial amount of 15O is implanted in the pipe/target frame/MUST2 masks. A dedicated AGATA activation measurement could be performed to cross-check this factor of two. |
| Fixed | e768s |
Mon Jul 22 17:07:39 2019 |
Marlène, Franck, François & Nicolas | BEAM | General | | Profiler conditions for measuring beam intensity |
| We checked that the measured beam intensity (present case 1.5e7 pps) is independent on the voltage on the profiler. Values from 93 V up to 177 V gave similar results. |
| Fixed | |
Mon Jul 22 19:13:45 2019 |
Kseniia | AGATA | General | | Current stats on 19Ne |
| Runs 112..125, still no joy... |
| Fixed | e768s |
Tue Jul 23 04:31:34 2019 |
Jenn & Christian | BEAM | General | | Diamond Scaler screenshot |
|
| Fixed | e768s |
Tue Jul 23 04:34:03 2019 |
Jenn & Christian | BEAM | General | | Beam intensity and profile check |
VAMOS OR: ~1200
BEAM INTENSITY ~ 2E7 |
| Fixed | e768s |
Tue Jul 23 06:49:54 2019 |
Jenn & Christian & Kseniia | BEAM | General | | Beam intensity and profile check |
VAMOS OR ~ 870
BEAM INTENSITY ~ 1.4E7 |
| Fixed | e768s |
Tue Jul 23 09:03:07 2019 |
Kseniia, Gilbert, Yorick | BEAM | General | | Beam intensity and screenshots |
The beam has been pretty stable since yesterday |
| Fixed | e768s |
Tue Jul 23 11:02:54 2019 |
Kseniia, Gilbert | BEAM | General | | Beam profile |
|
| Fixed | e768s |
Tue Jul 23 14:33:03 2019 |
Marlène, Yorick, Faïrouz & Nicolas | BEAM | General | | Cheking beam transmission from G1 profiler to VAMOS |
Goal:
Estimate beam transmission from profiler to VAMOS (FP)
We question whether the factor of two found yesterday (VAMOS/Profiler ~ 0.5) could be due:
1. to an incorrect measurement of the beam intensity with the profiler
2. a charge state equilibration in the target (LISE++ calculation indicates 8+/7+ = 85%/15%)
Same conditions as yesterday:
1. Beam intensity is reduced with the pepper pot 1/9 and by closing slits after the 15O target production and the accelerators so that the beam quality (emittance, etc...) is not affected.
2. VAMOS plate is removed to allow the direct beam detection
Results:
We measure in VAMOS with the LiF target and with the target ladder totally removed. In the latter case, direct beam 15O(8+) is sent in VAMOS and no charge state effect enter into the game.
1. Beam intensity at G1 profiler ~ 6.5e4 pps
VAMOS (FP) + no target ~ 3.8e4 pps
2. Beam intensity at G1 profiler ~ 3.8e4 pps
VAMOS (FP) + thick LiF (nb 1) ~ 2.0e4 pps
Discussion:
We find the same results as yesterday, e.g. a factor of two attenuation between the profiler and VAMOS. If part of this loss would happen in the pipe/target/MUST2 mask, this should be observed in AGATA which is not the case. Could it be that the PPAC in VAMOS is not as efficient as announced at the beginning of the campaign (98%)? This must be checked when we get beam back later on.
Note:
While doing the above measurement, we observed a factor of 3 loss between profiler AR.Gaz13 and G1.Gaz31. Numbers follows:
L3.GAZ42 AR.GAZ13 G1.GAZ31
2.1e4 1.5e4 4.1e3
1.4e5 1.0e5 2.5e4
??? 1.8e5 6.5e4 |
| Fixed | e768s |
Tue Jul 23 16:19:14 2019 |
Marlène | OTHER | Hardware | | VAMOS division |
VAMOS division was set 10 instead of 100.
CATS 1 & CATS2 scalers are sent to the two last channels of the scaler |
| Fixed | |
Tue Jul 23 17:09:43 2019 |
UK refugees | OTHER | Social | | Kipper issues. |
|
| Fixed | |
Tue Jul 23 23:22:56 2019 |
UK refugees | OTHER | Social | | Kipper issues. |
| I would mail you some but the postage is nuts those days! |
| Fixed | |
Wed Jul 24 12:44:55 2019 |
UK refugees | OTHER | General | | Fire out thanks to de Piffle |
|
| Fixed | e768s |
Wed Jul 24 16:24:18 2019 |
Nicolas | OTHER | General | | 19Ne / 19F analog connections |
|
| Fixed | e768s |
Wed Jul 24 17:21:27 2019 |
Diego | OTHER | General | | VAMOS Acceptance with different positions of the beam in the target |
|
| Fixed | e768s |
Thu Jul 25 11:05:18 2019 |
Francois de Oliveira | OTHER | General | | Previous Papers - alpha-branching ratios for states in the 4-MeV region |
| In the reaction 15N(7Li,t)19F, the ratio between the measured cross sections is R(3/2+/9/2-)>29. We should get the same ratio in 19Ne. In 19Ne, the 3/2+ state decays with Eg=4033 keV (80%), the second with 2632 keV (100%), gamma efficiency = 4% and 5.5%, this gives a ratio between the number of counts measured in the 2632 keV and in the 4033 keV > 29 x 100/80 x 5.5 / 4 ~ 50. |
| Fixed | e768s |
Fri Jul 26 02:27:48 2019 |
Marlène, Faïrouz, Franck, Bertrand, Sylvain, Diego, Nicolas | BEAM | General | | G1 profiler efficiency |
G1 profiler efficiency was checked against CATS1 for two beam intensities. Agreement between the two measurements is within 20%
Profiler -> CATS1
2.3e4 pps -> 1.8e4 pps
1.4e5 pps -> 1.16e5 pps
Conclusion:
G1 profiler is measuring correctly the beam intensity for these intensities |
| Pending | |
Fri Jul 26 11:25:46 2019 |
UK refugees | OTHER | General | | Be positive and the experiment will work if we put lead in our pencil |
|
| Fixed | e768s |
Fri Jul 26 13:48:41 2019 |
Marlène, Faïrouz, Bertrand & Nicolas | BEAM | General | | G1 profiler & VAMOS efficiency |
Factor of two between the profiler and VAMOS FP determination of incident beam is now understood.
Several effects were at work simultaneously and checked at 2 beam intensities (9e3 pps and 5e4 pps):
1. Profiler is using energy loss of the crossing beam particles to deduce the beam intensity. But the profiler was set to 15N instead of 15O.
We checked that for the same beam intensity of 15O the profiler gives 1.2e4 pps / 9e3 pps when tuned on 15N / 15O respectively. This amouts for 75% difference
2. Profiler tends to overestimate the real beam intensity by about 20% when compared to CATS1
Profiler / CATS1: 9e3 pps / 7.3e3 pps (81%)
Profiler / CATS1: 5e4 pps / 3.9e4 pps (78%)
3. VAMOS counting rates are lower than CATS1 by 20% which is consistent with the charge state distribution q(8+)/q(7+) = 80% calculated from LISE++
CATS1 / VAMOS: 7.5e3 pps / 5.8e3 pps (78%)
CATS1 / VAMOS: 3.9e4 pps / 3.0e4 pps (77%)
4. VAMOS PPAC efficiency was checked to be 100%: the PPAC logic signal is always present when triggerd by the drift chamber logic signal
Results:
By combining all previous factors and for 15O beam at the beginning of the experiment we obtain between the profiler and VAMOS FP a reduction factor of: 0.75 * 0.81 * 0.78 = 47%, CQFD!
Discussion:
This factor of two explains the difference we always observed when comparing estimated and measured g-ray yields. |
| Fixed | e768s |
Fri Jul 26 15:48:12 2019 |
Kseniia | AGATA | General | | Full stats with AGATA on 19F with the 15N beam |
Charge state 8 (plus zooms) and charge state 7;
Statistics of all the 15N runs combined;
Identification in VAMOS;
Alas, no clear peaks at 3908 and 2354. |