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 12:32:54 2018

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On 25/11/2018:

The beam was tuned for 6.0MeV 7Be 2+

Using 10mm aperture FCC = 12 pA

Run # 181125121226

<ul>
	<li>Run time: 7264s</li>
	<li>Pulser ON, as before</li>
	<li>Target: CH2 XVIII</li>
	<li>Beam: 6.0MeV 7Be 2+</li>
	<li>See attached picture 1 for sample spectrum of Far S2 front strip. See attached picture 2 for diode spectrum.</li>
</ul>

Run # 181125141350

<ul>
	<li>Run time: 1887s</li>
	<li>Pulser ON, as before</li>
	<li>Target: CH2 XVIII</li>
	<li>Beam: 6.0MeV 7Be 2+</li>
</ul>

During this run at 14:40 there was a very brief power outage. The run was stopped afterwards.

Check chamber setup:

Far S2 bias = -130.0V, leak I = 1.89uA

Diode bias = -70.1V, leak I = 0.00uA

Pressures (mBar):

<ul>
	<li>TPU1 = 1.0e-6</li>
	<li>TPU2 = 3.2e-7</li>
	<li>TPD1 = 6.5e-7</li>
	<li>TPD2 = 6.1e-7</li>
	<li>CHUP = Sensor Off</li>
	<li>CHDW = No Sensor</li>
</ul>

Preamps for Far S2 and diode are still drawing correct currents. The chamber setup appears unaffected by the brief outage.

At this point the pulser was disconnected from the oscilloscope - removing the load on the pulser. We expect the pulser peak position to change as a result.

After the outage we needed to retune beam for 6.0MeV 7Be 2+

Moved target ladder to position #2 - blank 10mm aperture. Had troubles finding beam, moved target to natC III. In diode spectrum we saw beam energies ~ 7-8MeV.

It turned out the bending magnet located right after the ion splutter source needed recalibrating. It was recalibrated using Hydrogen (A=1), Carbon (A=12), and Oxygen (A=16).

During the retuning, the pulser frequency was checked for both the 2.5 and 25Hz settings:

Pulser setting set to 2.5Hz

<ul>
	<li>Pulser frequency measured internally by scope: 2.095 -&gt; 2.096Hz</li>
	<li>Pulser frequency measured using scopes cursors: 2.092Hz</li>
</ul>

Pulser setting set back to 25Hz

<ul>
	<li>Pulser frequency measured internally by scope: 19.29 -&gt; 19.30Hz</li>
	<li>Pulser frequency measured using scopes cursors: 19.38Hz</li>
</ul>

After recalibrating the bending magnet, we switched beam to 6.0MeV 7Li 2+ to benefit from the higher beam current.

After tuning: FC4 = 1.25nA. Using blank 10mm aperture FCC = 96pA, using blank 3mm aperture FCC = 66pA -&gt; ~70% transmission attained.

Switched beam back to 6.0MeV 7Be 2+

Using 3mm aperture FCC = 7pA.

Opened Far S2 iris (was closed during retuning after power outage), set target ladder to CH2 XVIII

Run # 181125223800

<ul>
	<li>Run time: 35914s</li>
	<li>Pulser ON, 25Hz</li>
	<li>Target: CH2 XVIII</li>
	<li>Beam: 6.0MeV 7Be 2+</li>
	<li>Left running overnight</li>
	<li>See attached picture 3 for sample spectrum of Far S2 front strip. See attached picture 4 for diode spectrum.</li>
</ul>

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