The DSSD has been exchanged and aligned in 
November 2020. After bakeout at 140°C 
(externally, 120°C at internal temp. Sensor) 
for more than a week, the vacuum in the setup 
is roughly 4.5e-10 mbar.

After the bakeout the detector had to be 
realigned, it was lower by 1-2 mm. Using the 
line laser the realignment was done by 
touching only the screws on the far part of 
the base of the flange. These screws have been 
thightend by about a 1/4 turn after releasing 
the headless positioning screw accordingly.

On 30. and 31.03.2021 we did some testing with the 6 BaF detectors.

Trigger & threshold:
With a threshold at ~250 keV, each detector has an trigger rate of about 0.5kHz due to internal activity.

Energy spectra
All detectors showed the Na22 lines (511 + 1275 keV) and also the lines from internal activity.
The energy resolution was on the order of 8.5 - 11 keV, depending on the detector.

Time spectra
Raw TDC spectra showed self-stop peak.
TDC diff spectra (between detectors) show one main (sharp) correlation peak about 8ns = 30ch*0.293ns/ch off the zero. 
At very low intensity a time structure around this peak is visible in a region of 120ns around the main peak. This is not understood, the energy spectra look similar for all these time regions (above/on/below the main peak).
Additionally, the coincidence E-specta between detector 1 and 2 (gating on the main time peak), nicely showed only the 511 keV line from Na22 and some gras.

Overnight test run:
Det. 1, 2, 3, 4 with the Na22 source

lxg1275:/data.local3/e127/lmd_2021/test/
e127b_run0021.lmd
e127b_run0022.lmd
e127b_run0023.lmd
e127b_run0024.lmd
e127b_run0025.lmd
e127b_run0026.lmd
e127b_run0027.lmd
e127b_run0028.lmd
e127b_run0029.lmd
e127b_run0030.lmd
e127b_run0031.lmd
e127b_run0032.lmd
e127b_run0033.lmd
e127b_run0034.lmd

Gain matched HV settings: https://elog.gsi.de/esr/E127/289

Issues to solve:
- 2 missing HV channels
- Go4 Analysis not stable
- trigger not on Baf but on Si

The target overlap was optimized on xray and si rates.
The setting now is -10mm in SC9

attached are the settings for all MSCFs.
Settings are optimized for DSSD only, not BaF!

The full cycle length of ESR with 30 stacks is about 7:45 minutes, out of which 15.5 sec are with target switched ON.
This is without CMB/HTD in parallel.

1. before using stoch. cooling in ESR, boot and update the windows PC
2. better diagnostics for low energy/intensity beam-target overlapp in ESR is needed (either a clever analysis or a new detector)
more to come

The two attached plots show the collected Si data up to run0115.

Within this ~15h we have about ~70 counts in the peak region.

This translates to ~4.5 counts per hour.
And shall be compared to the 1 count/hour we had last year.

Attached is a plot of the uncalibrated energy spectra taken with the 90 degree xray detector for 118Te (red) and 124Xe (blue).
Shown is the region covering the K-alpha and K-REC peaks.

Calculating the ratios (Te/Xe) for K_alpha and K-REC energies from theory one gets:

K_alpha (theory): 0.9236  
K-REC   (theory): 0.9308

Without energy calibration we get the following ratio (using channel numbers):

K_alpha (exp): 0.9293  
K-REC   (exp): 0.9344

Taking into account that the channel numbers are not calibrated, the agreement is still very good.

In summary we can be sure that we have 118Te stored at 7AMeV.

Maybe, our degrader in FRS was removed by hand at (~13:40 26/05/21)
It is put back now (~13:10 27/05/21)
All runs taken in this period have to be double checked!

However, the xray lines from this night show Te for k_alpha and K-KREC

It is also possible that the readout of this degrader motor was just wrong due to its state as hand-controlled.