On 24/11/2018:
After the short test with 4.0MeV 7Li (see eLog #55) the beam was tuned for 4.0MeV 7Be 2+.
Run # 181124103943
- Run time: 43s
- Target: CH2 XVI
- Beam: 4.0MeV 7Be 2+
- Comment: Far S2 iris was closed!
Run # 181124104408
- Run time: 3971s
- Pulser ON, as before
- Target: CH2 XVI
- Beam: 4.0MeV 7Be 2+
After this run we checked the beam current:
FC4 = 10pA
Using 10mm aperture FCC = 4.5pA, using 3mm aperture FCC = 4.0pA
Attempted to increase beam current by adjusting bending magnet - optimum: 413.30mT
Run # 181124120558
- Run time 7930s
- Pulser ON, as before
- Target: CH2 XVI
- Beam: 4.0MeV 7Be 2+
See attached picture 1 for a sample spectrum from the S2 front strip. See attached picture 2 for the diode spectrum - the peaks from 7Be and 7Li are visible. Recall the diode has a 0.9um mylar protective foil in front of it.
Run # 181124141834
- Run time: 3362s
- Pulser ON, as before
- Target: CH2 XVI
- Beam: 4.0MeV 7Be 2+
Further attempts to increase beam current, ioniser increased from 24.0 -> 24.5A. FC4 = 15pA
Run # 181124154345
- Run time: 3609s
- Pulser ON, as before
- Target: CH2 XVI
- Beam: 4.0MeV 7Be 2+
Checked beam current: using 10mm aperture FCC = 4pA (time: 16:44)
Decreased oven temperature -> FC4 = 16pA
Run # 181124165221
- Run time: 4221s
- Pulser ON, as before
- Target: CH2 XVI
- Beam: 4.0MeV 7Be 2+
Collected background using carbon target:
Run # 181124180623
- Run time: 463s
- Pulser ON, as before
- Target: natC III
- Beam: 4.0MeV 7Be 2+
Beam current seemed unstable, run stopped, no actions taken. FCC ~ 5pA.
Run # 181124182304
- Run time: 3647s
- Pulser ON, as before
- Target: natC III
- Beam: 4.0MeV 7Be 2+
See attached picture 3 for a sample spectrum from the S2 front strip. The spectrum indicates hydrogen contamination is present on the carbon foil. See attached picture 4 for the diode spectrum.
After run: checked beam current. FC4 = 18pA. Using 10mm aperture FCC = 5.5pA.
Leaving for the night:
Far S2 leak I = 1.87uA. Far S2 and diode biases off.
19:25 pressures (mBar):
- TPU1 = 1.4e-6
- TPU2 = 3.7e-7
- TPD1 = 7.0e-7
- TPD2 = 6.6e-7
- CHUP = Sensor Off
- CHDW = No Sensor
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