| ID |
Date |
Author |
Category |
Subject |
|
44
|
Tue Jun 11 22:59:06 2024 |
Carsten | Accelerator | Identification / NTCAP started |
ESR is set-up in most parts.We are trying to identify our 229Th89+. It is more cumbersome then exspected because of the thick target an d the according energy loss, the pattern has changed compared to the last beamtime.
Just started the NTCAP with center frequency 246,5 MHz, 10 MSamples/s and -25db.
Center frequency will later be changed back to about 244,5 Mhz.
Directory 06-11-22_55_15 (correct time stamp). |
|
45
|
Tue Jun 11 23:46:06 2024 |
Carsten )))) | Accelerator | ID |
----
The frequency of the primary beam 238U82+ at the injection:
Ucool = -360 V
Frev = 1.974647 MHz without bump
Frev=1.97387 MHz with bump
---
ID:
246 MHz + kHz (+/- intensity) ID
521 +++ 238/92+
565 +. 230/89+
595 +++ 235/91+
642 +. 227/88+
670 +. 232/90+
693 +++ 237/92+ (strongest line)
721 +. 224/87+
744 ++. 229/89+ (our Th line)
767 ++. 234/91+
822 +. 226/88+
845 +. 231/90+
867 +. 236/92+
901 - 223/87+
922 +. 228/89+
942 +. 233/91+
1001 +. 225/88+
1020 ++. 230/90+
1039 +. 235/92+
1100 +. 227/89+
1211 + <- far off |
|
48
|
Wed Jun 12 09:43:57 2024 |
Carsten | Accelerator | Stopped NTCAP at 9:43 |
Setup at ESR is carried on - stopped the long-time NTCAP run from overnight, |
|
49
|
Wed Jun 12 12:12:44 2024 |
Konstantin Mohr, Julien Spahn, Jonas Koedel, Bernhard Maass | Accelerator | First Scraper Scan |
Thorium is in the ESR, we have time to check the beam position with the scrapers.
Beam Intensity in the ring 6E-5
Laser stabilization:
x1: -0.050
y1: -0.244
x2: 0.151
y2: -0.489
DS1VU: starting in negatives, touches beam at -0.1mm, beam gone at 0.5mm (laser gone)
due to betatron oscillation, vertical beam center is +0.5mm, beam diameter 1.2mm
DS1HA: starting in negatives, hf artifacts are gone at -25mm, touches beam at -17.2mm, beam gone at -16.4mm (laser gone)
DS1HA: starting in positives, hf artifacts are gone at +2mm, touches beam at -7.1mm, beam gone at -7.9mm
horizontal beam center is at -12.2mm, beam diameter 2.1mm (scraper is 8mm wide)
DS2VU: starting in negatives, touches beam at 0.4mm, beam gone at 1.0mm (laser gone)
due to betatron oscillation, vertical beam center is 1.0mm, beam diameter 1.2mm
DS2HA: starting in positives, hf artifacts are gone at 6mm, touches beam at -3.5mm, beam gone at -4.3mm (laser is scraped)
DS2HA: starting in negatives, hf artifacts are gone at -27mm, touches beam at -14.4mm, beam gone at -14.1mm (laser is scraped)
horizontal beam center is at -9.2mm, beam diameter 2.9mm (scraper is 8mm wide)
After the measurement of the ion beam position we superimposed the laser beam (see attachment 1). |
|
57
|
Thu Jun 13 02:05:04 2024 |
Carsten | Accelerator | Short Lifetime at 100 mA |
Lifetime still is short |
|
58
|
Thu Jun 13 10:06:35 2024 |
Constantine, Peter, Lukas, Jonas, Dounia, Carsten | Accelerator | Suspected Beam Troubles (is it really 229-Thorium?) |
From experience, the lifetime of the beam in the storage ring should be on the order of magnitude of hours, however, we observer beam lifetimes of the order of 10ish minutes. This suggests either a beam loss mechanism, a totally wrong species or a combination of both.
Yesterday (Elog entry 46) it was verified that the main beam is indeed 229-Thorium in the ESR.
2024-06-13: After discussion (phone) with Markus the lifetimes are reasonable and are dominated by recombination in the cooler. |
|
59
|
Thu Jun 13 10:32:29 2024 |
Konstantin | Accelerator | (Proper) Cooler settings |
We change the acceleration voltage of the electron cooler and observe the platform high voltage and the count rate at the particle detector south.
Cooler current at 100mA.
|
set voltage | measured voltage | Schottky width | |
-40 | | | |
80 | | | |
-40 | | | |
100 | | | |
120 | | | |
-40 | | | |
-60 | | | |
-80 | | | |
-100 | | | |
-120 | | | |
-38 | | | |
-40 | | | |
-42 | | | |
-44 | | | |
-46 | | | |
-48 | | | |
-40 | | | |
-38 | | | |
-36 | | | |
-34 | |
|
with scraper driven in (first signal drop in attachment 2):
|
set voltage | measured voltage | Schottky width | |
-40 | | | |
-38 | | | |
-36 | | | |
-34 | | | |
-32 | | | |
-30 | | | |
-20 | | 25kHz | |
-10 | | 48kHz | |
-0 | | 63kHz | |
-40 | | | |
-42 | | | |
-44 | | | |
-46 | | | |
-56 | | 7kHz | |
-66 | | 19kHz | |
-76 | | 40kHz
|
5kHz Shottky width at proper cooling conditions.
Modified bunching HF in beam process 7 and 10 in Paramodi folder "Ring HF" to get coasting beam conditions.
Afterwards manipilated the electron current from 100mA to 200mA to 50mA in BP8. |
|
61
|
Thu Jun 13 12:05:31 2024 |
Konstantin, Peter, Jonas | Accelerator | RF-amplitude |
To realize the shortest bunches possible, we check the bunch length as a function of two different bunching amplitudes. With the bucket fill set to 1.0 we observe the spectra compiled in attachment 1. The second attachment is recorded with a bucket fill 0f 0.2.
For an RF amplitude of 0.2 we do not observe bunches any more but a coasting beam. In the shottky spectrum we can resolve a shift of the signal and thereby adjust the electron cooler voltage to the bunching frequency to within 1 V.
U_e-cooler = -104410 V
I_e-cooler = 80 mA |
|
67
|
Thu Jun 13 14:56:09 2024 |
Stefan Schippers | Accelerator | Estimated beam lifetime: About 150 s |
Estimate of storage lifetime using my code 'hydrocal':
ion mass in u ...................................: 229
ion nuclear charge ..............................: 90
ion charge state ................................: 89
beam energy in MeV ..............................: 45501.1
beam energy in MeV/u ............................: 198.695
beam beta .......................................: 0.566309
beam rigidity in T m.............................: 5.4944
ring circumference in m .........................: 108.36
ring acceptance in mrad .........................: 2
ring temperature in °C ..........................: 25
ring vacuum pressure in mbar ....................: 3e-11
residual gas density in m^-3 ....................: 7.28767e+11
residual gas composition
Z %
1 93.43
6 2.23
7 0.75
8 3.29
18 0.3
cooler length in m ..............................: 2.5
electron current in A ...........................: 0.2
magnetic expansion factor .......................: 1
electron-beam diameter in mm ....................: 50.8
electron density in cm^-3 .......................: 3.62844e+06
cooler cathode temperature in meV ...............: 110
cooling energy in eV ............................: 109000
space_charge (0th iteration) in eV ..............: 44.3477
space_charge (1st iteration) in eV ..............: 44.341
transverse temperature in meV ...................: 110
longitudinal temperature in meV .................: 0.2
RR nmin .........................................: 1
RR lmin .........................................: 0
RR nele [no. electrons in subshell (nmin,lmin)] .: 1
RR nmax .........................................: 128
RR enhancement factor ...........................: 2.5
RR alpha in cm^3 s^-1 ...........................: 8.04602e-08
beam lifetime due to multiple scattering in s ...: 1.86e+06
beam lifetime due to single scattering in s .....: 7.51886e+07
beam lifetime due to charge capture in s ........: 3.5516e+06
beam lifetime due to stripping in s .............: 1e+99
beam lifetime due to recombination in cooler in s: 148.466
beam lifetime with electron cooling in s ........: 148.46
beam lifetime without electron cooling in s .....: 1.20121e+06
detector count rates for 1E6 stored ions and a residual gas pressure of 3e-11 mbar:
recombination detector from ecool (Hz) ....: 4575.41
recombination detector from res.gas (Hz) ....: 0.0545666
total rate on recombination detector (Hz) ....: 4575.46
ionization detector from res.gas (Hz) ....: 1.93798e-94 |
|
72
|
Thu Jun 13 22:08:07 2024 |
Dayshift | Accelerator | Problems with Accelerator? |
It seems to be that there are some problems with the injections in the ESR.
The last 2 accumulation cycles showed that wheter only a small amount of ions are injected into the ESR or the injection is missing.
Photos of the last 2 accumulation cycles are attached.
We ask if there are some problems with the ESR or with the SIS18, because the particle number in the SIS18 is also decreasing... |
|
74
|
Fri Jun 14 11:44:23 2024 |
Carsten Brandau | Accelerator | Cooling Time in SC7 increased from 9s to 12s |
Cooling Time in SC7 increased from 9s to 12s |
|
78
|
Sat Jun 15 03:46:34 2024 |
Night shift | Accelerator | GSI down |
All quadrupole and dipole magnets at SIS and ESR are out of order. Repairs can be expected earliest tomorrow evening. No shifts will take place before 6pm. Have a look at your mails for details. |
|
47
|
Wed Jun 12 09:17:43 2024 |
Carsten | | Tests of background with ionization pumps on (from monday) |
On monday the ionization pumps were switch on to test the background, and if it is possible to run with the pumps switched on.
Results and comments, see below:
Later some data were recorded with DAQ1 to allow for a more thorough analysis - beam is 238U38+ at 401 MeV/u - file 0013
Please note the data of this file was recorded after the figures below were taken.
In short, we have switched off the the ionization pumps because the conclusion is somehow ambiguous. Background rates from real photons are considerably low at ~5Hz and 10Hz for the small-band PMTs (see figure), Yet, PMT south goes up to 350 Hz and sees a lot of photons from the plasma discharge. The few Hz of the small-band detector would be suppressed by the length of the ion bunch / full lenght of the ring. But what is not known is how much it would actually influence the local vacuum of the ring.
Semjon Strohmenger also checked that the valve to the turbos in front and behind the gas-jet is open (--yes). They are running the whole beam time.
I exchanged the prepump at a pocket located between gas-jet and VUV detection set-up. Here after baking a leak was found, and the pocket was pumped with an "old" prepump.
Vacumm in the pocket was ~1mBar. Installed a more powerful Edwards XDS i10. When we left ESR the pressure in the pocket was already at low 10^-2 mbar and still decreasing.
May be this helps to improve local pressure. |
|
55
|
Wed Jun 12 22:48:55 2024 |
Carsten | | Beam Halo |
The seamingly short live time reported in entry 53 is due to a halo from a different isotope (?). It can be scraped away from the outside. The 229Th89+ primary beam can be scaped away from the inside and the halo stays. There is some spacial headroom between the two components.
Scraping from the outside using GE02DS3HG @+6mm starts to scrape the halo in the south arc. Please note that the +6mm means that you move past central orbit (scraper starts from -130mm).
Using this scraper allows for using the particle detector behind the e-cooler (GE02DD2_G). Position PD south in event mode is -30mm (has to be verified with higher ion beam intensity and electron current for larger recombination rate=.
The primary 229Th89+ is touched from the inside with GE01DB2IG @+14mm (north arc).
Position of GE02DS3HG in event mode is +8mm.
Electron current in SC8 is increased from 100mA to 200mA for faster cooling at low energy in order to condition after deceleration and before scraping.
positions particle detectors and scrapers
NA position -30 activated
NI +28
SA -28
DS3HG +10 |