Efficiency calibration in the lab

Detector: GEM1800 - 90 deg
Source: 210Pb
Distance: 167.5mm
Start time: 9:58:00 - 30.04.2021
Stop time:  10:01:09 - 30.04.2021

file name: e127b_run0005.lmd
avrg. rate: 50Hz
dead-time:  1%

Still rate peaks, probably the ESR kicker or some other external influence. 
So we have double triggers occasionally. This might slightly affect deadtime determination.

Efficiency calibration in the lab

Detector: GEM1800 - 90 deg
Source: 210Pb
Distance: 167.5mm
Start time: 9:26:58 - 30.04.2021
Stop time:  9:33:22 - 30.04.2021

file name: e127b_run0004.lmd
avrg. rate: 50Hz
dead-time:  1%

Still rate peaks, further investigations.

Efficiency calibration in the lab

Detector: GEM1800 - 90 deg
Source: 210Pb
Distance: 167.5mm
Start time: 20:39:54 - 29.04.2021
Stop time:  08:43:58 - 30.04.2021

file name: e127b_run0003.lmd
avrg. rate: 70Hz
dead-time:  1%

Rate spikes every ~2-3 sec. Need to be checked!

The UI-curve of the detector
U I
10 0.11
20 0.13
30 0.15
40 0.17
50 0.19
60 0.21
70 0.22
80 0.23
90 0.25
100 0.27
110 0.29
120 0.31
130 0.33
140 0.35
150 0.37

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 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.

This is the documentation of the source tests with the 2nd micron DSSSD of 2nd generation (label 3288-17, thickness 529um)

The detector is put into vacuum (~5e-6 mbar) in our test chamber. The source is positioned a few cm above (see fotos).
The Bayard-Alpert Sensor in the chamber has to be deactivated, otherwise the light emission will increase the noise on the DSSSD strongly and reduce its performance.

Additionally the current and voltage from the CAEN HV is monitored with the vulom scalers: ch.13(Icool) = current; ch.14(Ucool) = voltage. 


Source: mixes alpha [239Pu, 241Am, 244Cm]

File directory: lxg1275:/data.local3/test_data_2020/
QuickTest files: si2_test_mixed_source[X].root
lmd files:  Si2_run[XXX].lmd

DAQ Settings:
MADC gate   : 0 delay, 5000ns width
MSCF shaping: 2 us 
trlo config : e127.trlo (trigger=1/tpat=1 for Si, trigger=11 for vulom_scaler)


LMD runs:
-----------------------------
Si2_run001.lmd
Start: Fri 23.10.2020 16:19
Stop:  Mon 26.10.2020  8:36

File-Size: 20GB
Events:   ~53M
comment: 
source roughly centered
CAEN HV scalers not connected

-----------------------------
Si2_run002.lmd
Start: Tue 27.10.2020 16:01
Stop:  Wed 28.10.2020 13:26

File-Size: 12GB
Events:   ~32M
comment: 
source in one corner (x1, y1, see foto)
scalers should be connected now
current monitor range set to LOW
@start det_current=140nA det_voltage=90V
@end det_current=143nA det_voltage=90V

-----------------------------
Si2_run003.lmd
Start: Wed 28.10.2020 13:30
Stop:  Wed 28.10.2020 13:31

File-Size: 
Events:   
comment: 
ramping of det. voltage for scaler/U-F-Converter test
source in one corner (see foto)
scalers should be connected now
current monitor range set to LOW
@start det_current=140nA det_voltage=90V

-----------------------------
Si2_run004.lmd
Start: Tue 24.11.2020 12:50
Stop:  Tue 24.11.2020 

File-Size: 
Events:   
comment: 
source in one corner (x16, y16, see foto)
@start det_current=138nA det_voltage=90V
@end det_current=nA det_voltage=90V

-----------------------------
Si2_run005.lmd
Start: Tue 24.11.2020 14:57
Stop:  Tue 24.11.2020 15:11

File-Size: 
Events:   
comment: 
source in one corner (x1, y16, see foto)
@start det_current=144nA det_voltage=90V
@end det_current=nA det_voltage=90V

-----------------------------
Si2_run006.lmd
Start: Tue 24.11.2020 15:24
Stop:  Tue 24.11.2020 

File-Size: 
Events:   
comment: 
source in one corner (x1, y16, see foto)
Si_X & Si_Y cabling to MADC_0 and TDC_0 exchanged to get right order of channels/orientation
@start det_current=144nA det_voltage=90V
@end det_current=nA det_voltage=90V

Here is the analysis of the test runs with the 2nd DSSD (gen2) using the quick_si_plots.c script attached.

All 32 Si channels are working with acceptable performance. 

In run001, there are some additional low energy peaks in nearly all x-strips, which I do not understand yet. They are around 3 MeV and are not visible in the y-strips. It doesn't look like an electronic problem, because there are at least 4 
peaks, so not a low amplitude copy of the 3 major alpha peaks between 5 - 5.8 MeV.

However, in run002, the peaks have mostly disappeared, only in x6,x7,x8,x9 is a broad structure at somewhat similar energy... maybe this has to do with the small incident angle of the alphas?

Another run to confirm and double check this would be nice.

• measurement
  d1 = moved back from beam = 15 +/-.5 mm
  d2 = DSSSD frame width = 8.85 mm
  d3 = pg center on DSSSD = 7-7.5 bin = 21.7-23.2 mm = avg = 22.5 mm
  
  --> pg from beam in x = -46.4mm +/- 1.5mm
  --> pg on DSSSD from center ~ -3.28mm +/- 1.5mm
  
  
• simulation
  x = -46.5 mm
  y = 0 mm
  
  
• detector active area position
  x = (-73.35mm) - (-23.85mm)
  y = (-14.2195mm) - 23.5125mm
  
  
• SCRAPING: x=-35mm +/-0.5mm away from beam
  y=(-20mm) - (40mm)
  
  

• measurement
  d1 = moved back from beam = 16 +/-.5 mm
  d2 = DSSSD frame width = 8.85 mm
  d3 = pg center on DSSSD = 7.5 bin = 23.2 mm
  
  --> pg from beam in x = -48.05mm +/- 1.5mm
  --> pg on DSSSD from center ~ -3.28mm +/- 1.5mm
  
  
• simulation
  x = -48 mm
  y = 0 mm
  
  
• detector active area position
  x = (-74.35mm) - (-24.85mm)
  y = (-14.2195mm) - 23.5125mm
  
  
• SCRAPING:
  x=-35mm +/-0.5mm away from beam
  y=(-20mm) - (40mm)
  
  
  

Here is a representation how was the time management during E127. The time, what we could spend with measuring the 118Te(pg), was ~20% comparing to the given 6days.

For the efficiency vs E fit of the 90degree Xray detector I have used the following phenomenological funciton:

f(x) = a * (1-exp(-(x-c)/b)) * exp(-x/d)

Here the first exponent member is a saturation curve. This part describes the passing through of the two Be windows (chamber + before detector) and through the dead layer of Ge crystal. One needs a minimum energy to enter to the detecting Ge crystal = C parameter. b parameter = characteristic absorbtion E of these nondetecting layers.
The second exponent is an exponential decrease of the detector efficiency. Photons with higher energy are less detectable by the germaniums. The d parameter is the characteristic E for hard Xray and gamma (>40keV) detectability. 

https://www.amptek.com/internal-products/si-pin-vs-cdte-comparison

//Jan's comment: the tail of this function should more or less follow a linear trend a bit above than 40 keV.


In the attachment there is an example fit for 90 degree with combined 1. and 2. (before and after beamtime) calibration datasets. 
I made the fit with gnuplot:

degrees of freedom    (FIT_NDF)                        : 8
rms of residuals      (FIT_STDFIT) = sqrt(WSSR/ndf)    : 0.419915
variance of residuals (reduced chisquare) = WSSR/ndf   : 0.176329
p-value of the Chisq distribution (FIT_P)              : 0.994094

Final set of parameters            Asymptotic Standard Error
=======================            ==========================
a               = 0.00308376       +/- 0.0005144    (16.68%)
c               = 15.6259          +/- 2.035        (13.03%)
b               = 9.36888          +/- 3.16         (33.73%)
d               = 177.141          +/- 84.95        (47.95%)

Laszlo's out.

For all 3 detector the calibration data sets were combined to include the systematics in the fit results directly. Combining means not a weighted average, just simple all data points were included into the fit --> doubled efficiency value for most of the energies.
The g(x) = a * (1-exp(-(x-c)/b)) * exp(-x/d) function was used to describe the behavior of the Germanium detectors for the whole range of energies (global behavior). From these fits the 80keV outlier point was excluded. This is very strange that it doesn't follow the trend, it would be nice to find out why not.
Between 40-75keV a linear fit was carried out as well. This can also approximate quite well this local energy range, what we need for the K-REC peaks.
l(x) = m*x+e

All the fits were done by gnuplot, but it was also confirmed that ROOT gives us the same parameters + errors + chisquare. One just need to choose well the starting values :)


90° fits:
degrees of freedom    (FIT_NDF)                        : 8
rms of residuals      (FIT_STDFIT) = sqrt(WSSR/ndf)    : 0.419915
variance of residuals (reduced chisquare) = WSSR/ndf   : 0.176329
p-value of the Chisq distribution (FIT_P)              : 0.994094

Final set of parameters            Asymptotic Standard Error
=======================            ==========================
a               = 0.00308376       +/- 0.0005144    (16.68%)
c               = 15.6259          +/- 2.035        (13.03%)
b               = 9.36888          +/- 3.16         (33.73%)
d               = 177.141          +/- 84.95        (47.95%)

degrees of freedom    (FIT_NDF)                        : 4
rms of residuals      (FIT_STDFIT) = sqrt(WSSR/ndf)    : 0.283372
variance of residuals (reduced chisquare) = WSSR/ndf   : 0.0802998
p-value of the Chisq distribution (FIT_P)              : 0.988405

Final set of parameters            Asymptotic Standard Error
=======================            ==========================
m               = -6.22672e-06     +/- 1.836e-06    (29.48%)
e               = 0.00256426       +/- 9.873e-05    (3.85%)



145° fits:
degrees of freedom    (FIT_NDF)                        : 6
rms of residuals      (FIT_STDFIT) = sqrt(WSSR/ndf)    : 0.379472
variance of residuals (reduced chisquare) = WSSR/ndf   : 0.143999
p-value of the Chisq distribution (FIT_P)              : 0.990247

Final set of parameters            Asymptotic Standard Error
=======================            ==========================
a               = 0.0012346        +/- 0.0006794    (55.03%)
c               = 11.3754          +/- 4.075        (35.82%)
b               = 15.6961          +/- 13.2         (84.1%)
d               = 116.084          +/- 99.83        (86%)

degrees of freedom    (FIT_NDF)                        : 2
rms of residuals      (FIT_STDFIT) = sqrt(WSSR/ndf)    : 0.327728
variance of residuals (reduced chisquare) = WSSR/ndf   : 0.107405
p-value of the Chisq distribution (FIT_P)              : 0.898161

Final set of parameters            Asymptotic Standard Error
=======================            ==========================
m               = -2.39246e-06     +/- 1.278e-06    (53.42%)
e               = 0.000848859      +/- 7.329e-05    (8.634%)



35° fit:
degrees of freedom    (FIT_NDF)                        : 7
rms of residuals      (FIT_STDFIT) = sqrt(WSSR/ndf)    : 1.40676
variance of residuals (reduced chisquare) = WSSR/ndf   : 1.97896
p-value of the Chisq distribution (FIT_P)              : 0.0538635

Final set of parameters            Asymptotic Standard Error
=======================            ==========================
a               = 0.000114396      +/- 0.0002367    (206.9%)
c               = 14.3178          +/- 8.322        (58.13%)
b               = 16.7454          +/- 43.21        (258%)
d               = 79.7991          +/- 173.2        (217.1%)

degrees of freedom    (FIT_NDF)                        : 3
rms of residuals      (FIT_STDFIT) = sqrt(WSSR/ndf)    : 1.21233
variance of residuals (reduced chisquare) = WSSR/ndf   : 1.46975
p-value of the Chisq distribution (FIT_P)              : 0.220529

Final set of parameters            Asymptotic Standard Error
=======================            ==========================
m               = -3.7879e-07      +/- 3.143e-07    (82.99%)
e               = 7.31447e-05      +/- 1.788e-05    (24.45%)



> For the efficiency vs E fit of the 90degree Xray detector I have used the following phenomenological funciton:
> 
> f(x) = a * (1-exp(-(x-c)/b)) * exp(-x/d)
> 
> Here the first exponent member is a saturation curve. This part describes the passing through of the two Be windows (chamber + before detector) and through the dead layer of Ge crystal. One needs a minimum energy to enter to the detecting Ge crystal = C parameter. b parameter = characteristic absorbtion E of these nondetecting layers.
> The second exponent is an exponential decrease of the detector efficiency. Photons with higher energy are less detectable by the germaniums. The d parameter is the characteristic E for hard Xray and gamma (>40keV) detectability. 
> 
> https://www.amptek.com/internal-products/si-pin-vs-cdte-comparison
> 
> //Jan's comment: the tail of this function should more or less follow a linear trend a bit above than 40 keV.
> 
> 
> In the attachment there is an example fit for 90 degree with combined 1. and 2. (before and after beamtime) calibration datasets. 
> I made the fit with gnuplot:
> 
> degrees of freedom    (FIT_NDF)                        : 8
> rms of residuals      (FIT_STDFIT) = sqrt(WSSR/ndf)    : 0.419915
> variance of residuals (reduced chisquare) = WSSR/ndf   : 0.176329
> p-value of the Chisq distribution (FIT_P)              : 0.994094
> 
> Final set of parameters            Asymptotic Standard Error
> =======================            ==========================
> a               = 0.00308376       +/- 0.0005144    (16.68%)
> c               = 15.6259          +/- 2.035        (13.03%)
> b               = 9.36888          +/- 3.16         (33.73%)
> d               = 177.141          +/- 84.95        (47.95%)
> 
> Laszlo's out.

I have made also the inverse square law fits. We have data only for 90degre with the 241Am source, but both for the 1. and 2. calibrations. The 1. and 2. calibration data sets treated separate.
2 peaks were investigated, 59.5keV and 26.3keV, at two distances 184.8mm and 217.3mm. These distances are the sum of 4 distances:
a = width of plastic head. uncert.: +/- 0.05mm, measured with caliper.
b = width of the brass collimator. uncert.: +/- 0.05mm, measured with caliper.
c = width of protector plastic ring. uncert.: +/- 0.05mm, measured with caliper.
d= distance of the paper head. uncert: +/- 0.5mm, judged by the eye :)

The Be window and the dead layer of the Ge detector is not taken into account.

The distances calculated as D=a+b+c+d.

The conclusion is that the uncertainty coming from the distance measurements are negligible compared to the other uncertainties. The data obey the inverse square law.


> For all 3 detector the calibration data sets were combined to include the systematics in the fit results directly. Combining means not a weighted average, just simple all data points were included into the fit --> doubled efficiency value for most of the energies.
> The g(x) = a * (1-exp(-(x-c)/b)) * exp(-x/d) function was used to describe the behavior of the Germanium detectors for the whole range of energies (global behavior). From these fits the 80keV outlier point was excluded. This is very strange that it doesn't follow the trend, it would be nice to find out why not.
> Between 40-75keV a linear fit was carried out as well. This can also approximate quite well this local energy range, what we need for the K-REC peaks.
> l(x) = m*x+e
> 
> All the fits were done by gnuplot, but it was also confirmed that ROOT gives us the same parameters + errors + chisquare. One just need to choose well the starting values :)
> 
> 
> 90° fits:
> degrees of freedom    (FIT_NDF)                        : 8
> rms of residuals      (FIT_STDFIT) = sqrt(WSSR/ndf)    : 0.419915
> variance of residuals (reduced chisquare) = WSSR/ndf   : 0.176329
> p-value of the Chisq distribution (FIT_P)              : 0.994094
> 
> Final set of parameters            Asymptotic Standard Error
> =======================            ==========================
> a               = 0.00308376       +/- 0.0005144    (16.68%)
> c               = 15.6259          +/- 2.035        (13.03%)
> b               = 9.36888          +/- 3.16         (33.73%)
> d               = 177.141          +/- 84.95        (47.95%)
> 
> degrees of freedom    (FIT_NDF)                        : 4
> rms of residuals      (FIT_STDFIT) = sqrt(WSSR/ndf)    : 0.283372
> variance of residuals (reduced chisquare) = WSSR/ndf   : 0.0802998
> p-value of the Chisq distribution (FIT_P)              : 0.988405
> 
> Final set of parameters            Asymptotic Standard Error
> =======================            ==========================
> m               = -6.22672e-06     +/- 1.836e-06    (29.48%)
> e               = 0.00256426       +/- 9.873e-05    (3.85%)
> 
> 
> 
> 145° fits:
> degrees of freedom    (FIT_NDF)                        : 6
> rms of residuals      (FIT_STDFIT) = sqrt(WSSR/ndf)    : 0.379472
> variance of residuals (reduced chisquare) = WSSR/ndf   : 0.143999
> p-value of the Chisq distribution (FIT_P)              : 0.990247
> 
> Final set of parameters            Asymptotic Standard Error
> =======================            ==========================
> a               = 0.0012346        +/- 0.0006794    (55.03%)
> c               = 11.3754          +/- 4.075        (35.82%)
> b               = 15.6961          +/- 13.2         (84.1%)
> d               = 116.084          +/- 99.83        (86%)
> 
> degrees of freedom    (FIT_NDF)                        : 2
> rms of residuals      (FIT_STDFIT) = sqrt(WSSR/ndf)    : 0.327728
> variance of residuals (reduced chisquare) = WSSR/ndf   : 0.107405
> p-value of the Chisq distribution (FIT_P)              : 0.898161
> 
> Final set of parameters            Asymptotic Standard Error
> =======================            ==========================
> m               = -2.39246e-06     +/- 1.278e-06    (53.42%)
> e               = 0.000848859      +/- 7.329e-05    (8.634%)
> 
> 
> 
> 35° fit:
> degrees of freedom    (FIT_NDF)                        : 7
> rms of residuals      (FIT_STDFIT) = sqrt(WSSR/ndf)    : 1.40676
> variance of residuals (reduced chisquare) = WSSR/ndf   : 1.97896
> p-value of the Chisq distribution (FIT_P)              : 0.0538635
> 
> Final set of parameters            Asymptotic Standard Error
> =======================            ==========================
> a               = 0.000114396      +/- 0.0002367    (206.9%)
> c               = 14.3178          +/- 8.322        (58.13%)
> b               = 16.7454          +/- 43.21        (258%)
> d               = 79.7991          +/- 173.2        (217.1%)
> 
> degrees of freedom    (FIT_NDF)                        : 3
> rms of residuals      (FIT_STDFIT) = sqrt(WSSR/ndf)    : 1.21233
> variance of residuals (reduced chisquare) = WSSR/ndf   : 1.46975
> p-value of the Chisq distribution (FIT_P)              : 0.220529
> 
> Final set of parameters            Asymptotic Standard Error
> =======================            ==========================
> m               = -3.7879e-07      +/- 3.143e-07    (82.99%)
> e               = 7.31447e-05      +/- 1.788e-05    (24.45%)
> 
> 
> 
> > For the efficiency vs E fit of the 90degree Xray detector I have used the following phenomenological funciton:
> > 
> > f(x) = a * (1-exp(-(x-c)/b)) * exp(-x/d)
> > 
> > Here the first exponent member is a saturation curve. This part describes the passing through of the two Be windows (chamber + before detector) and through the dead layer of Ge crystal. One needs a minimum energy to enter to the detecting Ge crystal = C parameter. b parameter = characteristic absorbtion E of these nondetecting layers.
> > The second exponent is an exponential decrease of the detector efficiency. Photons with higher energy are less detectable by the germaniums. The d parameter is the characteristic E for hard Xray and gamma (>40keV) detectability. 
> > 
> > https://www.amptek.com/internal-products/si-pin-vs-cdte-comparison
> > 
> > //Jan's comment: the tail of this function should more or less follow a linear trend a bit above than 40 keV.
> > 
> > 
> > In the attachment there is an example fit for 90 degree with combined 1. and 2. (before and after beamtime) calibration datasets. 
> > I made the fit with gnuplot:
> > 
> > degrees of freedom    (FIT_NDF)                        : 8
> > rms of residuals      (FIT_STDFIT) = sqrt(WSSR/ndf)    : 0.419915
> > variance of residuals (reduced chisquare) = WSSR/ndf   : 0.176329
> > p-value of the Chisq distribution (FIT_P)              : 0.994094
> > 
> > Final set of parameters            Asymptotic Standard Error
> > =======================            ==========================
> > a               = 0.00308376       +/- 0.0005144    (16.68%)
> > c               = 15.6259          +/- 2.035        (13.03%)
> > b               = 9.36888          +/- 3.16         (33.73%)
> > d               = 177.141          +/- 84.95        (47.95%)
> > 
> > Laszlo's out.

"The e- cooler settings were the same for the 124Xe and 118Te beams" - Sergey --> speed of the ions is the same --> same MeV/u

E_beam = 10.0606MeV/u

The uncertainty on the cooloer values should be asked from Markus/Regina