ELOG CIRCE

AIDA GELINA BRIKEN nToF CRIB ISOLDE CIRCE nTOFCapture DESPEC DTAS EDI_PSA 179Ta CARME StellarModelling DCF K40

CIRCE

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Entry time:

Mon Dec 3 11:28:53 2018

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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

<ul>
	<li>Run time: 43s</li>
	<li>Target: CH2 XVI</li>
	<li>Beam: 4.0MeV 7Be 2+</li>
	<li>Comment: Far S2 iris was closed!</li>
</ul>

Run # 181124104408

<ul>
	<li>Run time: 3971s</li>
	<li>Pulser ON, as before</li>
	<li>Target: CH2 XVI</li>
	<li>Beam: 4.0MeV 7Be 2+</li>
</ul>

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

<ul>
	<li>Run time 7930s</li>
	<li>Pulser ON, as before</li>
	<li>Target: CH2 XVI</li>
	<li>Beam: 4.0MeV 7Be 2+</li>
</ul>

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

<ul>
	<li>Run time: 3362s</li>
	<li>Pulser ON, as before</li>
	<li>Target: CH2 XVI</li>
	<li>Beam: 4.0MeV 7Be 2+</li>
</ul>

Further attempts to increase beam current, ioniser increased from 24.0 -&gt; 24.5A. FC4 = 15pA

Run # 181124154345

<ul>
	<li>Run time: 3609s</li>
	<li>Pulser ON, as before</li>
	<li>Target: CH2 XVI</li>
	<li>Beam: 4.0MeV 7Be 2+</li>
</ul>

Checked beam current: using 10mm aperture FCC = 4pA (time: 16:44)

Decreased oven temperature -&gt; FC4 = 16pA

Run # 181124165221

<ul>
	<li>Run time: 4221s</li>
	<li>Pulser ON, as before</li>
	<li>Target: CH2 XVI</li>
	<li>Beam: 4.0MeV 7Be 2+</li>
</ul>

Collected background using carbon target:

Run # 181124180623

<ul>
	<li>Run time: 463s</li>
	<li>Pulser ON, as before</li>
	<li>Target: natC III</li>
	<li>Beam: 4.0MeV 7Be 2+</li>
</ul>

Beam current seemed unstable, run stopped, no actions taken. FCC ~ 5pA.

Run # 181124182304

<ul>
	<li>Run time: 3647s</li>
	<li>Pulser ON, as before</li>
	<li>Target: natC III</li>
	<li>Beam: 4.0MeV 7Be 2+</li>
</ul>

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):

<ul>
	<li>TPU1 = 1.4e-6</li>
	<li>TPU2 = 3.7e-7</li>
	<li>TPD1 = 7.0e-7</li>
	<li>TPD2 = 6.6e-7</li>
	<li>CHUP = Sensor Off</li>
	<li>CHDW = No Sensor</li>
</ul>

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