ELOG E127

K-REC cross sections A. Surzhykov

Attached is the header file needed for root analysis.

578

Wed Oct 13 15:09:04 2021

Jan

Collaboration

Attached are the theory K-REC cross sections as calculated by Andrey Surzhykov (August 2021).

They are done for 118Te52+ on H2 at 7.049 and 6.042 MeV/u as well as for 124Xe54+ on H2 at 7.049 MeV/u.


first column - photon angle (deg), second column - cross section (barn/sr). The results are given already in the laboratory frame.

Comment of Andrey on uncertainty:
Important question about theoretical model and, hence, accuracy of calculations. I used slightly improved "impulse approximation" that takes into account momentum and energy distribution of target electron (in initial state). By playing with the models for the Compton profile of target electron, I estimate the accuracy of calculations as 1 %. To be fair, it is rather conservative estimate. I suspect that for large emission angle (around 90 deg) accuracy is even better. But let us stay with 1 %.

577

Wed Jul 14 14:46:05 2021

We have measured the collimator geometry. The annotations of the variables can be found in the attached sketch

90° Detector GEM1800	Distance[mm]
A	2.4
B	10.05
C	2.1
D	35.025
145° Detector GEM3000	Distance[mm]
A	2.15
B	10.05
C	5.025
D	35
35° Detetektor GLP-2000	Distance[mm]
A	2.1
B	10.05
C	0
D	13

576

Thu Jul 8 14:07:19 2021

Table of ion energies calculated from cooler parameters

nominal energy	V_set	V_meas	I_set	E_ion	E_Error
6 MeV/u	3460.5 V	3364 V	50 mA	6.042 MeV/u	YY keV/u
7 MeV/u	4008.3 V	3913 V	50 mA	7.049 MeV/u	YY keV/u

Here is how the calculation works:

1. Find the voltage and current set values that were active during the measurement cycle.

2. These are only SetValues. For the current this is fine, but for the voltage you have to subtract an offset. This offset comes from the power supply and changes over time. It is measured regularly and the present offset you have to inquire with the ESR/cooler crew. For our beam time E127b in 2021 the offset is:

V_offset = -95 +/- ?? V (only for E127b)

The uncertainty has still to be discussed.

3. The space charge of the electron beam reduces the effective voltage seen by the electrons and thus reduces their energy. You have to calculate the space charge potential Phi_0 on the beam axis using the following formular:

using R_tube = 10cm and R_e-beam = 2,54 cm and all constants, you arrive at the ESR specific equation:

4. Now calculate effective Voltage and electron energy:

V_eff = V_set + V_offset + Phi_0

This time we measured the effective voltage for each energy, so we can actually use this values (V_meas) instead of V_set + V_offset.

E_e = e * V_eff

5. With E_e you can now calculate the ion energy by using the definition of the Lorentzfactor gamma:

gamma - 1 = E_kin/(m_0 * c^2)

In equilibrium, the left side of the equation is equal for both, electrons and ions in the cooler, leading to:

E_ion = E_el * M_ion/M_el

which gives the total energy of the ions.

NOTE:
In principle, this should be an iterative calculation, since the potential depends on beta and is then used to calulate beta or ion energy. But in practice a single iteration is precise enough, if beta was a good estimate.

575

Thu Jul 8 13:39:34 2021

Jan

Electron cooler parameters

Below are the results from the e-cooler voltage offset measurments done by Regina Hess et al. using the voltage divider (VD).

--7 MeV-- 
Sollwert GECEBG1E: 4008.3 V     
Measured at VD: 3913 V
Offset: -95.3 V

--6 MeV-- 
Sollwert GECEBG1E: 3460.5 V     
Measured at VD: 3364 V 
Offset: -96.5 V

Below are the cooler parameters from ParaModi for our production runs.

--7 MeV/u--
UE: 3842.7V
IE: 50mA
BG1E: 4008.7V
BG1E dU: 120V

--6 MeV/u--
UE: 3290.833V
IE: 50mA
BG1E: 3460.4809V
BG1E dU: 120V

--energy calculation--
as described here 

-- uncertainty --
for E108b we agreed on 10%
maybe further discussion is needed

574

Thu Jun 24 09:43:01 2021

The unpacker used for the production runs of E127b is located at 
/u/litv-exp/unpacker/unpackexps/e127_TO_2021_with_ECL

It is also aliased for litv-exp user as: E127_unpack

This is for the data structure as documented here:
https://elog.gsi.de/esr/E127/346

As of now, this is compiled for ROOT v6-18-04 located here:
/cvmfs/csee.gsi.de/root/618-04/bin/root

573

Wed Jun 23 12:29:35 2021

Jan, Sophia

Efficiency of the x-ray Detectors

For the x-ray detectors, efficiencies have been measured, before and after the experiment was performed. 
The preliminary results of the determined efficiencies can be seen in the attached plots

572

Tue Jun 8 15:06:17 2021

measured beam lifetime after the second deceleration using parallel plate Schottky detector and the RSA5103 spectrum analyser. Analysis code can be found here:

https://github.com/xaratustrah/e127_scripts/

The plots here were produced using the script:

https://nbviewer.ipython.org/github/xaratustrah/e127_scripts/blob/main/lifetime_calculator.ipynb


UPDATE 2022-06-30:

Life times have been slightly corrected. Please see attachment.


Filename	Start Frame	Correct Lifetime [s]	Mean [s]
pgamma_lifetime-2021.05.25.21.56.37.593_on.tiq	29500	1.43	
pgamma_lifetime-2021.05.25.22.02.16.618_on.tiq	29500	1.55	1.49
pgamma_lifetime-2021.05.25.22.07.22.369_off.tiq	53500	1.75	
pgamma_lifetime-2021.05.25.22.13.24.787_off.tiq	34900	1.89	1.82

571

Wed Jun 2 09:14:04 2021

Attached is the exported Telegram chat.
There is the simple PDF and the zip-file containing the chat in json-format as well as all media files.

570

Mon May 31 14:38:33 2021

Sophia

Runlist for X-ray detector calibrations after the experiment

The by Jacobus Swartz created table in entry 335 extended by the calibration after the experiment.

569

Mon May 31 10:08:42 2021

Sun May 30 14:48:09 2021

Sun May 30 14:40:55 2021

Jan, Sophia

Detectors

real detector assignment

************************************
GEM1800 @ 90deg (xray1) 
GLP2000 @ 35deg (xray2)
GEM3000 @ 145deg (xray3)
************************************

Was noted wrongly in most calib runs.

566

Sun May 30 14:38:09 2021

run0216 - X-calib. 90-ba 35-pb

Efficiency calibration in ESR after experiment

************************************
GEM1800 @ 90deg (xray1) 
GEM3000 @ 35deg (xray2)
GLP2000 @ 145deg (xray3)
************************************


Detectors: 90 + 35 
Source @ 90deg: 133Ba_lo
Source @ 35deg: 210Pb
Distance: each
Start time: 14:46:46 - 30.05.2021
Stop time:  20:11:08 - 30.05.2021

file name: e127b_run0216.lmd
avrg. rate: 330Hz
dead-time:  3%

565

Sun May 30 13:23:26 2021

run0214 - X-calib. 90-ba 145-ba 35-am

Efficiency calibration in ESR after experiment

************************************
GEM1800 @ 90deg (xray1) 
GEM3000 @ 35deg (xray2)
GLP2000 @ 145deg (xray3)
************************************


Detectors: 90 + 145 + 35 
Source @ 90deg: 133Ba_lo
Source @ 145deg: 133Ba_hi
Source @ 35deg: 241Am_hi
Distance: each
Start time: 13:22:38 - 30.05.2021
Stop time:  14:28:09 - 30.05.2021

file name: e127b_run0214.lmd
avrg. rate: 1150Hz
dead-time:  8%

564

Sun May 30 11:32:06 2021

run0213 - X-calib. 90-am 145-pb 35-ba

Efficiency calibration in ESR after experiment

************************************
GEM1800 @ 90deg (xray1) 
GEM3000 @ 35deg (xray2)
GLP2000 @ 145deg (xray3)
************************************


Detectors: 90 + 145 + 35 
Source @ 90deg: 241Am_hi
Source @ 145deg: 210Pb
Source @ 35deg: 133Ba_hi
Distance: each
Start time: 11:31:47 - 30.05.2021
Stop time:  13:10:14 - 30.05.2021

file name: e127b_run0213.lmd
avrg. rate: 700Hz
dead-time:  6%

563

Sun May 30 10:24:20 2021

run0212 - X-calib. 90-pb 145-am