On 05/04/18:

At 9:00 the pressures read ~10mBar inside the chamber (static vacuum). We began venting the chamber.

During venting the cable daisy chain on top of the preamp boxes was removed, the downstream preamp box was removed. It was decided to also removed the central preamp box and its respective spacer box to avoid any collisions when removed the downstream lid.

By 9:20 the chamber was vented. The downstream aperture was removed. The downstream lid was removed, the S2-> vacuum feedthrough cable was changed.

The downstream S2 was remounted into the chamber, and the downstream aperture was remounted onto the chamber collar.

During this process the 4mm diameter collimator for the diode was ready, we decided to also mount this in front of the diode since the chamber was already vented.

The central aperture was removed and the central lid was then removed. The 4mm collimator with 0.9um mylar was installed in from of the diode. The 0.9um mylar was held in place on the collimator using an epoxy.

The central lid was reinstalled, followed by the central aperture on the collar.

The downstream aperture was set to 1.5mm, and the central aperture was set to 14.0mm, opening the irises ready for pumping.

At 10:45 Ecodry 1 and 2 were switched on, the gate valve was cracked open. During roughing the downstream preamp box was mounted followed by the central preamp box.

At 11:03 the T1600 Backing valve was opened and chamber pressures read ~1.0e-1mBar. The 7 turbos were started. (Turbos Up 1 and 2, Turbos Down 1 and 2, Turbo Entrance 3, Turbo CSSM, and T1600)

The +15V, -15V, +ve test, and HV bias cables were reconnected to the central and downstream S2 preamp boxes, and also the diode preamp.

Preamp power was applied, +15V draws 1.5A and -15V draws ~0.6A as expected.

At 11:15 CHUP = 2.6e-5mBar, CHDW = 6.8e-5mBar. Central S2 bias ramped to -130.0V, leak I = 3.51 uA. With the preamp lid off a 0.1V pulser on RAL X CH 1 produced a 1.5V amplified signal with ~200mV noise.

I recollected the bias vs leak I curve for the downstream S2. See S2_2323-18_496um_Bias_Vs_Leakage_Current_050418.png

RAL 1 CH1 looked clearer than yesterday, 0,6V pulser setting produces 3V signal. However there was a strange reflection on the end tail of the pulser peak. I mounted both preamp lids but still saw the reflection. This effect dissapeared after disconnecting the diode preamp test input from the daisy chain with the S2 preamp boxes. I replaced this with a 50 ohm terminator.

We adjusted the downstream S2 RAL thresholds (they were 15mV to begin with except RAL I (100mV) which was adjusted yesterday)

Now the thresholds are:

We tried starting the DAQ using an OR trigger from the downstream S2, however we were presented with an error: Too Many Bad Events

We tried disconnecting all of the RAL ECL outputs except RAL I's, we still recieved the error.

We tried increasing the pulser amplitude setting from 0.2 -> 0.6V, still recieved the error.

We tried restarting the FAIR DAQ, after restarting we got good events. We can see a pulser peak and two alpha peaks.

We reconnected the ECL outputs for RAL II -> RAL VIII to the DAQ OR trigger

Note: ADC 2 (module 3) still shows strange "TDC-Like" behaviour, so we avoid this module.

The first 8 channels of RAL I still show alot of noise, we increased RAL I threshold from 90 to 100 mV

Triggering DAQ only on downstream S2, we see a dead time ~ 9% and trigger rate ~3700Hz

I tried removing the downstream preamp box lid and checked both the preamp -> feedthrough and also the preamp -> IDC convertor box connections on the preamp PCB. I resealed the preamp box lid.

Check on RAL I CH1 (downstream S2) noise: for pulser setting 0.5V amplified peak has height 2.8V noise 100mV

Check on RAL X CH 1 (central S2) noise, for same pulser setting amplified peak has height 2.8V noise 100mV, signal to noise ratio ~ 3.57% for both channels

We then connected the central detector ECL signals to the 3rd and 4th MALU 4532 Logic modules in the CAMAC crate. RAL X -> "R" sent to ADC 4, RAL "S" and "Q" sent to first 16 channels of ADC 5. Channel 31 of ADC 5 is diode. Currently the diode CFD threshold = 200mV. RAL X -> "Q" thresholds were all kept at 15mV.

We set the DAQ trigger to an OR of all 129 channels (64 from each S2 and 1 from diode)

Started DAQ, dead time 9%, trigger rate 3500 Hz, event mult = 52.5.

We decided to run an alpha spectrum.

Pulser Settings:

• Fall Time = 100us
• Rate = 10Hz
• Delay = 250ns
• Ampl = 0.5V
• Pol = POS
• Pulse Top = Tail
• Atten = 1X
• Clamp = OFF

14:55 started DAQ for 15 min alpha spectrum, save name: /Remote_Objs/RData_1/180405140038

Dead time = 71%, trigger rate ~ 1600Hz, event mult = 57.6