Run started 13:40

Target density 4.3e11, Beam injection is ~1e7, Pressure in the ring is ~1e-10 mbar.

Detectors have been moved IN with servo motors only (left arm pot = 36.5 mm, right arm pot =37.7 mm

Time between injections is 12 seconds. Beam is in the ring for 3 seconds of the cycle.

System wide checks OK

Temperatures OK

Leakage current plot attached -> temperature fluctuations (attachment 1)

ADC data items stats (attachment 2)

Merger and tape server OK

All histograms and statistics zero'd

14:17

Cave access required. No beam

15:24

No beam. System wide checks ok. Merger ok.

Attatchment 3: stats

Attatchment 4: Temperatures generally okay, 3 were red before reload, one red after reload.

Attatchment 5-8: Waveforms. Layout 7 and 8 look different from yesterday, consistnely different after several reloads.

Attatchment 9: Leakage current

Attatchment 10: LOWENERGYEXEY PLOTS

17:12

Tunning beam. System wide checks ok. Merger ok.

Attatchment 11: stats

Attatchment 12: Temperatures generally okay, 3 were red reloaed and stayed red but not so high.

Attatchment 13-16: Waveforms. Were the same as previous check.

Attatchment 17: Leakage current. They are tunning the beam so its a little bit changed.

19:28

Still hvae unstable noncooled beam, currently being worked on.

Tunning beam. System wide checks ok. Merger ok.

Attatchment 18: Temperatures generally okay, 3 were red reloaed and stayed red but not so high and were slighlty dicrease.

Attatchment 19-22: Waveforms. Were the same as previous check.

Attatchment 23: Leakage current. Slowly increasing from last check in, highest its been but conditions are not great at the moment.

21:10

We did not have any update about the beam. They still work on it.

Tunning beam. System wide checks ok. Merger ok. Stats were ok.

Attatchment 24: Temperatures generally okay, Same 3 were red and they increased a little bit. Nothing too concerning.

Attatchment 25-28: Waveforms. Were the same as previous check.

Attatchment 29: Leakage current. Contining to increase by small amount from last check.

16:09

Check Leakage current: (see attachment 1)

Check NewMerger tab: (see attachment 3)

Check Fee temperatures: all green (see attachment 5)

Check statistics tab: ADC data items (see attachment 2)

                                 ADC coincidence-info #8 (see attachment 6)

                                 Good events (see attachment 4)

 Check Spectrum Browser tab: (see attachment 10)                 

Check the following plots:

                                         LowEnergyXYTotalDSSD0 (see attachment 9)

                                         LowEnergyExTotal (see attachment 7)

                                         LowEnergyEyTotal (see attachment 8)

Check system wide checks tab: White Rabbit error counter test result: Passed 0, Failed 5 (see attachment 11)

Run stopped for pulser tests 16:13

07:00

Run 12 started. D+ beam is incident on the target at 1.5 MeV

Beam intensity in the ring is ~4e7 particles

Target density shows some fluctuations but is ~1e11 atoms/cm2. Target temp 35K

Detectors are positioned fully out (Left arm 18.86mm and right arm 19.8 mm ) and are not moving

Ring pressure looks OK, YR09 E target sensor seems unaffected by the target currently reads ~5e-11 mbar.

Beam is in the ring for ~15s.

Temps and system checks OK

Leakage current OK

Merger and tape server OK

Horizontal beam position 8 mm and vertical beam position 0mm for overlap with target.

Statistics - attachment 1

Energy histogram - attachment 2

XY plot - attachment 3

We see high rate at 1.5 MeV in left dssds but very little in right dssds. XY plots also show counts are concerntrated in a very circular distribution.

07:15

Gleb has just called and requires access to the cave to check on a turbo pump in the source.

Ring vacuum looks good

Beam will be down for 10-15 minutes only hopefully. 

07:45

Beam is back in the ring but injection requires optimisation.

09:00

There are some issues with the source that require a few hours to resolve. Potentially until 7 or 8 pm tonight. We have about an hour before work starts.

We have done a quick test of the motors and moved the left and right arms in using the pnuematic only.

New position left arm = 62.71 mm , right arm = 64.6 mm.

We observed the rates in left detectors went up significantly. In the right detectors we observed little increase.

See attached xy plot - attachment 4

See attached energy histogram - attachment 5

Beam intensity has dropped significantly - below 1e6 particles so even at in positons we see few counts at the moment.

09:25

Source has degraded pretty rapidly so beam will be stopped for now.

Detectors moved back out.

Target nozzle moved from X= -13000, Y=2500 to X= -11000, Y=2500. S1 has dropped to 5e-10 mbar.

Note Gleb mentioned that last night it was likely a large proportion of the ions stored were molecular hydrogen not deuterium.

16:18

Temps and system checks OK

Leakage current OK

Merger and tape server OK

18:10

Temps and system checks OK

Leakage current OK

Merger and tape server OK

19:38

Operators are trying to optimize some beam. For now the beam is lower than it should be probably because is easy to work with the source like that.

Temps and system checks OK

Leakage current OK

Merger and tape server OK

9:30 Bias remained stable overnight - 60V 2.95 uA.

10:00 No grounding attached initailly. Pulser ON, lots of noise across all ~250-300 kHz across biased detector. Waveforms and histograms saved to /tmp. Pulser width for aida 6 ~300 channels. Aida 7,8 similar, aida 5 producing no ADC data. 

11:00 Grounding connected as in elog 181. Rates decreased to ~180-250 kHz. Waveforms and histograms saved to /tmp. 

12:00 Bias slowly increased too 100V giving a leakage current of ~3.5 uA which was stable for several hours. Bias varied between 60V and 100V for noise reduction perposes, 80V deemed least noisy at the time, noise still ~180-200 kHz

13:30 New grounding trialled. Bottom detector removed from pulser and grounding loops so that only the biased detector is grounded. Bias set to 80V

14:00 Rates significantly reduced for aida 6,7,8 - aida5 still producing no ADC data. Rates are in range 15-50 kHZ with noisy channels accounting for most of the rates. Waveforms and histograms saved to /tmp. Pulser peak on aida 6 ~300 channels. 

16:00 Aida 5 fee investigated to reason it is not producing data. FEE was not properly connected to ERNI connector due to incorrect installation of black adaptor card mount. Adaptor card mount reinstalled and fee remounted. Aida 5 now produces ADC with similar rates to aida6,7,8. 

During investigation of aida5, aida4 and 5 were swapped. Config files relating to MAC addresses, polarity etc of FEES has been updated. Elog 175 will be appended to include this swap.  

19:00 Bias set to 80V, DAQ running with pulser off to allow for alpha detection overnight. 

DAQ was left running last night from 19:30. Detector bias 80V with a leakage current ~3.4 uA. Pulser OFF.

Observed alphas in spectra overnightin the 20,000 to 28,000 channel range for the pn side and 36,000 to 44,000 range on the nn side of the detector. Zero energy noise peak is at channel 32000.

Alphas checked for AIDA5 and AIDA6 (pn) with ~150 alphas counted using a range 20,000-26,000/27,000 depending how large the noise peak tail is. Attached spectra show the spectra for the 4 ASICs of AIDA5 and 6.

Baking tent, frame and trays fully removed from CARME chamber. Removal of baking frame required removing air lines from upper gate valve and repositioning of vacuum hose connecting turbo pump to backing line and turbo power cable. Some difficulty encountered removing upper baking frame now the target support frame is assembled. Small modification seperating section in two would aid future installation and disammebly. 

Baking trays removed with difficulty. Main baking tray bent to extract from the frame -> updated design required for future bakeout cycle. 

VI tests performed on the upper and lower detectors. Upper detector shows characteristic curve (attached plot), lower detector shows no response to increased voltage. Multimeter used on adapter boards with resistance of ~18.5 kΩ observed between bias pins for the upper detector. Open line seen between bias pins on the lower detector, some connections observed for other pins on the board -> requires further investigation.  

NOTE - Channel 0 on bias supply is unstable, should not be used. 

 Most equipment for installation of FEE's and coolant manifolds found, assembley of FEE holders started. Full list of current swagelock inventory as follows:

Current pulser widths excel spreadsheet attached

09.58 DSSSD bias OK - attachment 1 

Ambient temperature +16.1 deg C FEE64 temps OK - attachment 2 

ADC data item stats OK - attachment 3 
 aida15 asic #2 high rate - asic u/s

system wide tests OK *except* aida09 - attachments 4-5 
 aida09 WR status 0x20 aida09 WR timestamp incorrect cf. all other FEE64s

per FEE64 Rate spectra - attachment 6

per FEE64 1.8.L spectra - attachments 7-8 
 aida14 pulse peak witdh 58 ch FWHM
 aida11 pulse peak witdh 48 ch FWHM

per FEE64 1.8.W spetra - 20us FSR - attachments 9-10
 

12.00 

aida09 WR timestamp issue resolved by FEE64 reboot 


14.10 

Safety pins removed from detector motion system. CB performs one, complete DSSSD movement cycle. Zero all histogram and stats per FEE64 Stat spectra ( log scale ) and 
ADC 
data item stats for the complete DSSSD movement cycle - attachments 11-12 
No change observed in DSSSD leakage currents during DSSSD movement cycle. 

15.35 

Resolved issue from previous elog. Begin background run writing data to disk.
ASIC check load 
Start DAQ G22-88/R1 background alpha 
EG&G Ortec 448 Pulser OFF 
ASIC settings 2024Jan20-12.02.08 
slow comparator 0x64 ( all FEE64s *except aida15 asic #2 0xff ) 
All histograms set to zero

DSSSD bias OK - attachment 13 
FEE64 temps OK - attachment 14 

WR timestamps OK - attachment 15 

ADC data item stats - attachment 16 
aida15 asic #2 u/s - rate c. 250k 

ADC data items/s Merger, Tape Server & Merger stats - attachments 17-19 
 data rate to disk c. 2Mb/s dominated by aida15 asic 2

Connected Leybold Ionivac IE514 to Leybold Combivac CM52 Vacuum Gauge Controller

Rear panel - power ON

POST checks OK

Change parameters by

select PARA

select <-> to display Sen

select PARA to display S-on

select <-> to display HAnd

select PARA and hold for 7s

select CH to select CH3

select -> hold for 2s 

With CARME gate valve closed for c. 24h CARME chamber pressure is 6.43e-5mbar @ 13.34, 6.52e-5mbar @ 14.15


15.45 CARME Leybold turbo restarted

16.06 1.58e-6mbar, 3.5e-5mbar (RGA station), leak rate 3.6e-10 mbar.l/s

16.27 9.44e-7mbar, 3.3e-5mbar (RGA station), leak rate 3.6e-10 mbar.l/s

16.39 7.67e-7mbar

17.00 5.85e-7mbar, 2.5e-5mbar (RGA station), leak rate 2.60e-10 mbar.l/s

17.20 4.83-7mbar, 2.3e-5mbar (RGA station), leak rate 2.17e-10 mbar.l/s

Baking octagon moved into position along with the bottom insulation and heaters
 

Following overnight pumping by Leybold turbo pump

09.12 6.26e-8mbar, 2.8e-6mbar (RGA station), leak rate 5e-12 mbar.l/s

09:52 6.08e-8mbar, 2.8e-6mbar (RGA station), leak rate 8e-12 mbar.l/s

10.10 6.02e-8mbar, 2.8e-6mbar (RGA station), leak rate 8.5e-12mbar.l/s 
KM says leak cart currently isolated CARME chamber + RGA cart - no He
has been used around chamber this week so figure represents noise.

10.36 5.94e-8mbar, 2.8e-6mbar (RGA station), leak rate 4.7e-12 mbar.l/s

10.40 KM isolated RGA station (@RGA station) from CARME chamber to replace current RGA (FC sensor) with a more sensitive RGA (with multiplier + FC sensor) 

CARME vacuum pressure (with no backing) will rise somewhat during this process

11.17 1.35e-7mbar

11.20 New RGA install complete, backing line opened, CARME pressure recovers in < 10s to 5.83e-8mbar

14.08 5.59e-8mbar, 2.7e-6mbar (RGA station), leak cart disconnected (by KM)

Cables for neg and neg ion pumps connected with cables trailed out of the octagon through back and front of the octagon. Neg-ion pump connectors are labelled with Kapton 
tape to prevent confusion with neg connectors. Baking jacket has been partially constructed and will be completed tomorrow. 

Detector is not biasing as it has in previous tests. Last bias 15/1/22 see previous elogs, max leakage current ~10 uA at 150V

Detector bias increases well above 10uA for voltages as low as 30-40V. Optical windows covered, Y09 valves closed, large ion pump OFF and both ion gauges OFF produces similar results but with a slightly lower leakage current.

Grounding and pulser cables removed from FEEs and jumper attached to nn bias adaptor card - no change. Bias module swapped out - no effect. NIM rack shows expected voltages (6,12,24) on multimeter.

AIDA03 - disconnected. Behaves as expected. Get waveforms and pulser peak. Pulser peak FWHM ~ 70 channels, noise transients observed.

AIDA02 - Not producing ADC data

AIDA01,04,05,06,07,08 - Very high rates - noisy

FEE mounts for 5,6,7,8 disassembled to access adaptor boards. No sign of debris which could cause short on adaptor boards. 

Adaptor boards removed and checked against spares with multimeter. Both show same characteristics. Pins on feedthrough checked using multimeter. No longer see -18.5 KOhm between bias pins, no see 140 kOhm which is similar to bias pin to non bias pin from prevous tests.

Camera on interaction chamber removed and replaced with foil, no change. 

Ion gauge (Edinburgh group) turned ON

Decided to move detectors using motors. Movement caused change in bias characteristic of the detector. Initial movement was 50 repetitions in and out over which the bias was increased from 10V to 140V. Over this range the detector exhibited diode like behaviour. The difference between the in and position and out position caused a 0.5 uA difference in leakage current. Once stationary, the current was stabel at 140V but after 20s current increased rapidly and tripped.  

Increasing bias again to 30V while stationary (out position on motors) gave 7.3 uA , going to 60V tripped again. 

Moving the detectors IN but keeping stationary gave a stable current at 30V of 4.2 uA increasing to 70V tripped again. Turning off the gauge reduced the current at 30V to 2.9 uA and 70V to be be ~15.5 uA. Opening an optical window at 70V saw no change in leakage current. 

Possibility thermocouple attached to or around the detector may have come loose within the chamber? Thermocouples outisde of chamber removed from thermocouple flange so they don't interact with outside of chamber. 

Detector biased to 60V - 10 uA. Detector position moved in and out 20 repetions, during movement current dropped to 2.85 uA. After motion stopped leakage current remained stable at 2.85 uA. Optical window opened no change. Torch light shone into optical window - increase in leakage current to 3.5 uA. Torch off - return to 2.85 uA. 

Motion started again for 50 repetitions to test stability of leakage current. Current varies between 2.84-2.88 uA during movement, settles to 2.85 uA once motion stopped. 

FEE holder reassembley. Involved turning off bias, unplugging bias cables and rebuilding assembley. FEE holders reaasembled with FEEs reconnected. Water cables, HDMI, ethernet, power connected. Bias turned off and on during reassembley multiple times to check for changes. Each time bias at 60V remained 2.85uA. Each time lower voltages appear to show diode like response in leakage current output. 

Pulser connected and FEEs turned back on. Aida05 appears not producing ADC data rates 8 kHz on statistics page -investigate further. Aida06 rate ~70 kHZ can see pulser. Aida07, 08 nn bias show rates ~300 kHZ possible not enough bias for nn side. Rate for all FEEs yesterday (unbiased) was 200-300 kHZ except for AIDA03 disconnected and AIDA02 which wasn't producing ADC data. Photo of Aida06 spectra attached (log scale for pulser). 

FEEs turned OFF. Bias left on 60V - 2.85 uA see if stable overnight, stable for approx 2.5 hours before leaving cryring. Detector moved to OUT position, pin back in. 

To do - Grounding, reduce noise, waveforms,  investigate AIDA05, how high can we bias?  

To log into appc218 desktop:
same login and password as to carme@atppc022.gsi.de

To start anydesk

1. make sure a monitor is plugged into the carme computer!
2. ssh into npg@carme-gsi
3. su terminal
4. killall anydesk
5. systemctl start anydesk
returns an anydesk backend, service and tray
Anydesk is now accesible 
 

Moved pneumatic motor in and out several revolutions

Biased detector up to 100 V, I ~ 12.4 uA ambient temp c. 21 deg C

Moving detector in increased leakge current to ~14.5 uA, moving detector out dropped leakage current back to ~12.4 uA

aida05 - pulser width 21 chn (slightly lower than yesterday)

aida01 - pulser width 124 chn

aida02 - double peak (is not currently grounded)

aida03 - 183 chn

aida04 - 212 chn

Attachment 1     1.8.L spectra p+n FEE64s

Attachment 2      per FEE64 rate spectra

Attachment 3      aida05 1.8.L, 1.8.W and rate spectra

Attachment 4      FEE64 temperatures - OK

Attachment 5      per FEE64 ADC data event stats - rates for aida01-aida04 significabtly lower than yesterday presumably due to detector bias -100V

Attachments 6 & 7 per FEE64 1.8.W spectra

Attachment 8      1.8.L spectra for n+n FEE64s

regrounded aida02 back to cryring ground - required removing star configuration of all fee grounds and making a new

aida05 - pulser width 30 chn 

aida01 - pulser width 300 chn

aida02 - 220 -> double peak gone 

aida03- 190

aida04 - 200

Perhaps star configuration isn't as tight as before - re tighten star section

Re tightened section -> no impact on pulser widths

Moved detector in using pneumatic -> no impact on pulser widths

Added a grounding cable from the 19 inch rack to the same CRYRING ground that the fees are connected too. Stats around 2-3k, slow comparator = 0x64, bias=100v, I=12.18 uA

aida01  ~ 260

aida02 ~ 177

aida03 ~ 178

aida04 ~ 187

aida05 ~28

Removed CRYRING ground. Fees and rack connected together still. 

no change

Bias supply module is floating

ion pumps off, gauge off -> no change in waveforms, leakage current dropped to 8.7 uA

aida01 ~ 255

aida02 ~ 176

aida05 ~ 26

Removed all vacuum systems and motors power from 19 inch rack power. Connected to the rack are now: NIM bin, network switch, 2 inputs to mains relay, raspberrypi, pi dlink usb connector, VME crack

aida01 ~ 220

aida02 ~ 154

aida05 ~ 27

aida03 ~ 181

aida04 ~ 193

Moved power cable for 19 inch rack to CRYRING 'clean' power source

aida03 ~ 211

aida04 ~ 212

aida01 ~ 317

aida02 ~ 215

aida05 ~ 29

Reconnected CRYRING ground 

aida01 ~ 301

aida02 ~ 203

aida05 ~ 28

aida03 ~ 181

aida04 ~ 191

Current status 17:00:
All CARME vacuum equipment is off (turbo, SIP power modules, NEG power modules, gauges) - roughing pump is on but is valved off from the turbo which is valved off from chamber

Motors and motors pi are off. Detectors are fully out and the pin has been reinserted. 

Bias ON 100V, 8.5 uA. Pulser ON, all equipment connected to 19 inch rack power ON.  Jumper is on link 1 for nn bias adaptor card only. 

measurement 1 -string
intermediate (smaller) chamber - 2144 (mm) circumference,  measured half circumference 1072 mm 
outer (larger) chamber - 2160 (mm) circumference, measured 1/4 circumference 540mm

measurement 2 - foil tape
intermediate (smaller) chamber - 2156 (mm) circumference,  measured half circumference 1078 mm 
outer (larger) chamber - 2172 (mm) circumference, measured 1/4 circumference 543mm

Difference from centre to flat surface on outer chamber is 344 mm on drawing -> say 346 mm radius -> 2174 mm circumference
Part 620FBM600 from pfeiffer intermediate chamber 690mm diameter, 2168mm 

Measurements of parts of CARME frame to the target frame as a reference for target frame position.

Attachments 3+4 show clearance between CARME frame and target frame just below interaction chamber from inside and outside of the ring. Attachment 5 is clearance in same section but above interaction chamber

Attachment 6 - measurement between outer edge of CARME frame and inner edge of target frame - 165mm

Attachment 7 - measurements between outer edge of CARME frame and inner edge of target frame - 455 mm 

Attachment 8 - measurement between lower edge of CARME frame and lower edge of target frame - 1245 mm

Attachment 9 - measurement between top of VAT valve and lower edge of target frame - 233mm (left arrow), 216mm (right arrow)

Waveforms and discriminator ON. Pulser re-connected to all fees via daisy chain. V=100v, I=8.36uA

Pulser peak widths (ch FWHM)

aida01 ~ 109

aida02 ~ 98

aida05 ~ 24

aida03 ~ 118

aida04 ~ 136

Attachments 2, 3 & 4 1.8.W spectra, 20us FSR

Attachment 5 FEE64 temps OK

Attachment 6 per FEE64 ADC data item rates OK

Attachment 7 per FEE64 rate spectra

Merger reset following procedure from https://elog.ph.ed.ac.uk/DESPEC/36. Keywords for future elog search NetVar, xfer links

Pulser walkthrough R94

EG&G Ortec 448 Pulser settings

Amplitudes 90,000 - 10,000 @ 10,000 step

Attenuators x5 IN

t_r 50ns tau_d 50us

polarity + (- polarity via Cooknell SA1)

Frequency int relay

Motors box turned ON, motors pi ON, dlink network connector ON. Motors box, pi and dlink all in 19 inch rack but power supply is from a uk mains extender daisy chained to vacuum mains extender.  19 inch rack power supply remains on clean line.

Pulser peak widths (ch FWHM)

aida01 ~ 105

aida02 ~ 98

aida05 ~ 23

aida03 ~ 132

aida04 ~ 144

See attachments 8 & 9

Detectors moved in by pnuematic only. Leakage current increased to 9.6 uA (same as leakage current during bias ramping)

Pulser Walk R95

Pulser settings as above

See attachments 10 & 11

Detectors moved back out . Motors box, pi and dlink still turned ON. Leakage current to 8.36 uA

Pulser Walk R96

Pulser settings as above

See attachments 1 & 12

Jumper removed from nn bias fee adaptor board (aida04). No jumpers on any adaptor boards now. V=100V, I=8.36uA

See attachments 14 & 15 - 1.8.W spectra 20us FSR

Pulser on 90,000 x5 attenuate

aida01 ~ 123, centroid ~14691

aida02 ~ 106, centroid ~ 15038

aida05 ~ 23, centroid ~ 14414

aida03 ~ 125, centroid ~ 50838

aida04 ~ 127, centroid ~ 51754

Jumper reinstalled on aida04 nn bias. Note only link 1, link2 inaccesible with fee inserted into ERNI. See attachment 13

aida01 ~ 123, centroid ~14688

aida02 ~ 114, centroid ~ 15034

aida05 ~ 23, centroid ~ 14411

aida03 ~ 118, centroid ~ 50854

aida04 ~ 135, centroid ~ 51697

Pulser off. Background run to be left overnight started 14:24 R97. V=100v, I=8.36 uA.

Internal CARME installations complete. 

• New strain reliefs (flange side) installed on each cable harness.
• 2x sets of SAES UHV1400 NEG pumps installed and connected to 2x power feed-through flanges -> continuity checked OK -> 3x UHV1400 modules gives a resistance of 7.4 Ohms, 2x UHV1400 modules gives resistance of 4.8 Ohms. 
• Pins B & D open circuit wrt ground ( DMM OL > 20M ? )
• Pin C connection to ground OK 
• Internal thermocouples connected. Middle thermocouple connected to strain reliefs, right thermocouple connected to a standoff on the detector, left thermocouple floating (see attached images). Resistance on thermocouples checked for middle and right thermocouples ~ 4 Ohms per thermocouple. 

V-I tests performed prior to closing CARME. All detectors show expected curve, but light leaks are present. Pressing my hand against the aluminium shield yielded 0.5-1.5 uA drop in leakage current. Could not turn off lights for the test due to other people working in the cave. Will repeat test when closed. Temperature in the cave ~ 21.5 C. 

Both chamber sections have now been closed. Wire seal appeared correctly positioned immediately prior to final close. Bolts closing the wire seal have been tightend to 100 Nm, plan to increase to 140 Nm tomorrow. DN100 feed-through flanges have been tightend with a torque of 24 Nm. 

Plan is to move chamber back onto the ring tomorrow and get ready for leak testing. 

The wire seal has been tightend further to 160 Nm. Open neg feed-through flange has also been fully tightend. 

The CARME chamber was then slid back onto the aluminium frame on the ring. Two carriages were damaged during the sliding process, which have now been replaced. Carriages were replaced by lifting one end of the upper frame section using the crane by only ~1mm. This was sufficient to slide out the broken carriage and replace it (see images to be uploaded)..  It appears there is some deformation in the rails on the temporary frame as CARME is slid across, which resulted in the damaged carriages -> further refinements are required for future slidings. The height of the chamber has been checked using the laser allignment.  

The turbo pump has also been mounted to the top of the chamber . Current plan is to close to the interaction chamber tomorrow and begin pumping.  

23/06/23

The CARME chamber and interaction chamber were connected and section 9 has been fully closed. New valves have been installed on the interaction chamber, in addition to new diamond windows. A leak cart has been connected to the backing line of CARME. Before begining the pumpdown, the manual valve between the interaction chamber and the electron target was closed. 

The pumpdown was started at 17:15,  the valve on the scroll pump was very slowly opened to not damage the berylium window. By 18:00 a pressure of 1 mbar was achieved and the turbopump was activated. By 18:20 a pressure of 2E-3 mbar was achieved, the ion gauge was activated and briefly flashed 5E-4 mbar but this is over its limit so the gauge shutdown. At 19:20, 1.3E-3 mbar was achieved, the ion gauge was activated but the reading was 1.7E-4 mbar which is still over its limit. The turbo fan was not working and temperatures on the turbo were ~50C and increasing, so it was decided to close the main gate valve and turno off the turbo overnight in order to fix the fan.

A bias test of the detectors was also performed while in vacuum, T=20.5 C. All detectors show expected V-I curve and the leakage current is ~1-2 uA lower than the previous test in air, probably due to reduced light leaks. The top right detector did initially produce >10 uA at 20 V but the adaptor card was not properly seated on the p-n feed-through. Seating the adaptor card correctly yielded the expected V-I curve. Further inspection of the pins on this feed-through will be performed tomorrow.  

24/06/23

Overnight the pressure had increased to 0.8 mbar. Opening the gate valve decreased the pressure by an order of magnitude. The turbo fan was fixed and the turbo was re-activated, the pressure dropped to 1E-3 mbar level within 20 minutes.  Ion gauge was turned on after 30 minutes with a pressure of 3.7e-5 mbar. Pump down plot and comparison to previous pump downs will be uploaded in a seperate elog. Turbo pump maximum temperature reads 46C and has been consistent for several hours. 

V-I tests completed for the right hand side detectors. Leakage currents ~0.4 uA higher than yesterday which is consistent with the increase in temperature of ~ 0.5-0.7C. 

Attached are images showing the messages for normal turbo-pump operation

23/06/23

Pumpdown started with the scroll pump 17:15 . The turbo-pump was started 17:55. Gate valve was closed and the turbo turned of at 19:20 due to no working fan on the turbo. 

24/06/23

Ion gauge was activated at 11:56, P= 3.7e-5 mbar. Attached pump-down curves begin from when the ion gauge was activated.

The first plot is a comparison was a calculation for water outgassing in the chamber (which has many assumptions) but is a good guide on the expected 1/t decrease in pressure over time. The second plot is a comparison to previous turbo pump-downs in 2020 and 2021. In 2020 the chamber was bare with no instrumentation. In 2021, kapton and detectors were installed, but the pump down was conducted in several stages. Pressure readings are taken from the gauge reader in the cave, the vac plot viewer online appears to show a slightly different reading. 

 25/06/23

10:30 P= 7.11e-7 mbar. Opened valve on leak cart and saw a large increase in the pressure (above ion gauge level). Closed valve to leak cart, pressure recovered quickly (1.28e-6 mbar after ~ 30 mins). Pressure in the leak cart ~3e-3 mbar. Possibly small trapped volume between valves on the leak cart. Opened valve to leak cart again, no pressure increase observed in the chamber.  

11:40 Leak testing. Base leak rate ~5-6e-10 mbar.l/s.  Spraying helium on the seal between the bottom of the interaction chamber and the newly installed valve saw a large increase to  >1e-8 mbar.l/s. Closer attention suggests the leak may be from the rotatable flange on the bottom of the interaction chamber. An increased leak rate to 1e-9 mbar.l/s was also observed on the diamond window on the inside of the ring. Spraying around wire seal and feed-through flanges on chamber on the inside of the ring gave a leak rate of 6e-10 mbar.l/s. This may be a small leak, but is most likely noise on the leak detector or drifting helium to the large leak on the interaction chamber. Cannot determine prescence of small leaks while the large leaks are active. Closing valve to leak cart saw the leak level drop to <1e-12 mbar.l/s. 

Attached images show sites of the major leaks on the interaction chamber.