This is reachable and change-able via outside Internet

Jessica Tomlinson wrote:

I have attached a pdf of a series of slides with some multiplicity and hit pattern plots on, also a list of cuts. As well as this I looked at how many 'good hits' (explained in pdf) I am getting per event. Before Christmas I found that the code was not clearing the raw arrays read in by MIDAS and so unless a new piece of data filled the array channel number the data from the last event was being read into the next event too. It was only clearing the 'data(i) arrays which is what the data is unpacked as. I have now got it clearing both so data is not read in for multiple events.

? 

As far as I am aware it has never been necessary to explicitly zero the 'raw' (or packed) data arrays containing the

ADC/TDC data and active channels in each event. Usually it is only necessary to zero those elements of the 'unpacked'

arrays which contain event data.

I have attached a pdf of a series of slides with some multiplicity and hit pattern plots on, also a list of cuts. As well as this I looked at how many 'good hits' (explained in pdf) I am getting per event.

Before Christmas I found that the code was not clearing the raw arrays read in by MIDAS and so unless a new piece of data filled the array channel number the data from the last event was being read into the next event too. It was only clearing the 'data(i) arrays which is what the data is unpacked as. I have now got it clearing both so data is not read in for multiple events.

 I have attached some single strip energy vs time plots to show that the structure seen in the collective E vs t plots is in each strip. 

Attachments 1 and 2 show two different strips in S2-2 with no cuts. You can see that the 3 loci are different to one another in the single strips as well as in the combined S2-2 E vs t plot shown in attachment 3. Attachement 3 is plotted after applying the following cuts: equal energy in the front and back of each detector, low energy cut, must be a hit in each detector, multiplicity must be greater than 3. The 3 different loci are a beam pulse apart. The energy cal is 40keV/chan. 

Attachments 4 and 5 show energy vs time for single strips in S2-1 with no cuts. Attachment 6 shows the combined front strips in S2-1 after the same cuts as above for the combined S2-2 plot have been applied. Now there are 2 loci in the same beam pulse which are still there after the cuts. Not sure what the second line is. The energy cal in attachment 6 is 80keV/chan.

 Attachment 1 shows S2-1 energy vs time with a gate on energy in S2-2 being greater than 9MeV i.e. See previous elog also posted today for explanation.

I have sorted the 4.11MeV/u data runs (the ones which had the common stop mode on the TDCs) and applied the following cuts:

1. There must be a hit registered in each side of the detectors.
2. equal energy must be deposited in both sides of the detectors.
3. Low energy cut is applied to each detector.
4. Must have a hit in the TDC for the front strips.
5. Must have multiplicity greater than 3.
6. Must have hits in both S2-1 and S2-2.
7. Particles must hit at 180 degrees to in the detectors. (back spoke cut)

Looking at the back spoke in S2-1 vs back spoke in S2-2 plot cut number 7 should be changed to +/- 3 back strips to ensure no particles are being cut out due to position straggling in the gas.

Plotting S2-2 energy vs time with these cuts gives attachment 1. I need to redo the timing calibration for S2-2 as strip 96 has the wrong offset and the resolution needs to be improved. The protons can be seen clearly as they punch through the detector and around 8MeV. I have also attached as attachment 2 the monte carlo plot for S2-2 at this energy. There are two monte carlo codes one for 21Ne beam scattering and one for the reaction which means the number of each type of event are not correctly proportional, in the data there is far more scattering. Here you can see the protons from ~4-8MeV lying underneath the alpha line. The time spread in the actual data of the proton/alpha line is about 25ns whereas in the monte carlo it is about 10 ns for combined alpha and protons. 

Because the protons will punch through the detector at approx 8MeV I believe that the points after this could be alphas. Attachment 3 shows the projection for the polygon which selects particles after the protons in the energy vs time plot. As can be seen from the energy projection the energy dips where you would expect it to for alphas, however there are some higher energy points and I am not sure what these might be.

I then plotted Energy vs time in S2-1 gating on energy in S2-2 greater than 8.2MeV. This plot is shown in attachment 6. Attachment 4 shows the Monte Carlo simulated energy vs time for 18F in S2-1, with attachment 5 shows simulated energy vs time for scattered 21Ne in S2-1. I plotted these separately as they have the similar timing and so cant be seen separately on the same plot. Here you can see the 21Ne clearly in the data, so some of the protons are depositing more than 8.2 MeV in S2-2. If I change the cut so that the energy in S2-2 must be greater than 9MeV and plot energy vs time for S2-1 again the 21Ne is no longer visible (will not let me attach this file due to capacity so I will attach it in a new elog entry straight after this one). The energy spread of the points in the S2-1 energy vs time plot cut on what could be alphas in S2-2 gives the correct energy spread for 18F in the monte carlo simulated data.

Next:

• Redo timing calibration for S2-2
• Look at gas out run
• Work out how to separate lower energy alphas and protons
• Work out what higher energy points in S2-2 could be.

 Energy vs Time plots

I updated the monte carlo written by Alex to include time and also created new SRIM tables for 250 Torr rather than 300 Torr. I ran the Monte Carlo for a beam energy of 4.44MeV/u and plotted energy vs time for each detector. It should be noted that there are 2 codes, one for scattering 21Ne(p,p)and one for the reaction 21Ne(p,a) and the number of scattered particles as opposed to the number of reaction products from (p,a) are not what is expected in the data but the energies and timing are.

Attachment 1 shows energy vs time in S2-1 (downstream-heavy ion detector) from the data runs at 4.44Mev/u. Beam pulses are 85ns apart. The cuts on this include: equal energy cuts between the front and back of each detector removing interstrip hits, coincidence hits between S2-1 and S2-2, must be a hit in the front and back of each detector, phi cut so that particles must hit S2-1 and S2-2 at 180 degrees to one another. A feature not shown in the monte carlo is the second weaker line of particles, hitting the detector just after the first stronger line. I am not sure what this is, could be beam scattering off the entrance window or from N gas left over in the chamber?

Attachment 2 shows the same plot (energy vs time) simulated with the monte carlo for scattering reactions and for the (p,a) reaction. This shows that the reaction is dominated by beam scattering from the target H2 gas. The 18F extends to lower energies as shown in the monte carlo and there are some lower energy points in the data  (Att 1) which could correspond to this, however I am not sure whether this is F or beam scattering from the entrance window which also produces an extended range of energies. 

Attachment 3 shows energy vs time data plot in S2-2(upstream - light ion detection), at same energy and with same cuts as for s2-1 in Att 1. Again comparing this to attachment 4 which shows the Monte Carlo calculated energy vs time plot for S2-2 the data is dominated by scattering events. The small number of events which happen after 8.5 Mev (protons will punch through the detector after this) could be alphas. The Monte Carlo shows the alpha particles have a wider energy range than the protons. 

Other plots

I ran a 'gas out' data set to see how much scattering was coming from the entrance window to the chamber. There is no gas out run for 4.44 MeV/u so I used the one at 4.11MeV/u. This shows that there was some scattering from the window getting through the cuts described above, in S2-2 they go no higher than 8 MeV which makes me think it is scattering with protons because of the punch through energy. To check it was from the window I checked a run where there was no target and no window in the chamber and saw nothing after the cuts above. 

Other plots I am looking at include: time(S2-1) vs time (S2-2), energy(S2-1) vs energy(S2-2), energy vs strip for each detector, time of flight difference between S2-1 and S2-2 vs energy difference between two detectors, difference in theta (front strip) vs sum energy of two detectors, time of flight vs energy difference. 

eol

 Energy calibration for S2-2 was done using the pulser data (set 6 of the pulser runs) to calculate the offsets and alpha run R186 to calculate the gains and constant. For S2-1 pulser walkthrough 6 was also used to calculate the offsets and the gains calculated using run 31 which is 21Ne beam scattering from Au/C target. The constants were then calculated by fitting a least squares fit to the alpha peaks from run 186 and the gold scattering peak from run 31 energy vs peak position plot.

TDCs were calibrated with different sources for each detector. For S2-1 the offsets were calculated using the TDC spectra for the 21Ne on Au/C (Run 31) data. For S2-2 the run 23 was used which is a pulser run.

Currently applying equal energy and coincidence cuts to the data and plotting using Monte Carlo to compare to what I am seeing in the data. Plotting things such as Energy in S2-1 vs Energy in S2-2, back strip in S2-1 vs back strip in s2-2, energy sum.

Attached. Book 13 is split into 4 sections as otherwise the file is too big for the elog to accept.

Attached is a spreadsheet summarizing all the run information from the experiment.

1) PD run with gas (250Torr) - done

2) Pump down to 50 Torr - done

3) PD run - done

4) Take data (PD out) at 50Torr ~2 hrs. ~110epA - done

5) Pump out - done

6) PD run (no gas) - done

   a) remove 5mm collimator and run without gas, ~100epA (no PD) - done

7) Complete H2 venting process - done

8) Open up, sources in (window off) - done

9) Pump down - done

10) alpha data (some of the S2-1 inner strips look  very ill indeed , but all but one or two show clear triple-alpha peaks.  - done

11) pulser walkthrough - done

12) vent and open up - done

13) dismount detectors and re-entrant flange - done

14) pub!

Done - finished at 7.30pm, pitcher of ale methinks. 

Beam current dropped to 85 epA at the start of the shift, operator checked for reasons and decided to change
stripper foil. That brought the current back up, but it started decreasing again, so from run to run slits were
gradually opened further to keep FC0 current at about 100 epA.
I forgot the part about saving and clearing the spectra after every run, so runs 171-177 were summed together.

No major problems presented, A pluser walk was performed at the begining of the shift run161 S2-1 front, run162 S2-2 front, run163 S2-1 back and run165 S2-2 back.

Runs 166, 168, 169 are void due to bad scaler reading

Two times the control room reported the dipole magnet tripped but beam was recovered within few minutes. FC0 readings range 150-120epA

S2-1 L. current 17.60uA @ 16:00 and 18.85uA @ 23:10

S1287 data files R1_*.gz to R100_*.gz transferred from directory
tuda2:/data2/data/S1287 to directory tuda3:/data3/data/S1287

This releases c.18Gb of space in the tuda2:/data2 filesystem

Sarah informed me that Jamie was performing the sorting and saving of spectra differently and didn't know what exactly to do so I will not be performing any sorting.

01:40 Run 144 Stopped

01:45 Run 145 Started

03:43 Run 145 Stopped

Stripper foil changed, still seeing fluctuations so the problem could be in the SC-LINAC

03:57 Run 146 Started

Rate durring run 146 has been a little low, will ask for more at the run change.

05:50 Run 146 Stopped

FC0 averaged 65pA for run146.  Got it back up to 100pA for the next run.

05:54 Run 147 Started

06:15 No beam, lost a SC cavity.  Run 147 stopped

06:42 Beam back.  Run 148 started and stopped due to low scaler 1 reading

06:43 Run 149 Started

07:10 Rate dropped back down to ~4200, FC0 = 60pA.  Stopped run 149, saved and zeroed the histograms

FC0 back up to 100pA

07:13 Run 150 Started

Run139

Started 19:05:03
Stopped 20:36:36

Rates were reaching well above 8500, ops were measuring 160 epa on FC0 so they decreased it to 120 epa before starting next run.

Run 140

Started 20:42:12    - Scalers were acting up, stopped the run
Stopped 20:55:50

Run 141

Started 20:56:14
Stopped at 22:50:02

Rates were too low (~4289), ops were measuring 70 epa on FC0, got ops to increase current to 120 epa before starting next run.

Run 142

Started 22:56:34
Stopped 23:32:13

Rates were reaching above 9000 again, ops were reading 150 epa on FC0.  Brought it back down to 115 epa before starting next run.

Run 143

Started 23:36:38 - scalers were acting up, stopped the run
Stopped 23:37:46

Run 144

Started 23:40:17


****submitting summary early in case browser crashes again.  will update with any changes.

Please note that these procedures are not perfect and other small operations not listed may need to be carried out. Some mistakes may still exist in these procedures which could introduce significant risk if not spotted and corrected during the process. These should only be carried out by people confident they understand the system and the purpose of each step, giving due consideration to each step to ensure it is appropriate and safe.

In other words, don't blame me if it all goes horribly wrong!

For run 123:

Beam outage for ~15 min but not stopping run.

FC0 = 120pA when we got beam back.

We'll let the run go 15 min longer.

Run 125 stopped early because of strange rate values on scalar 1.

Sorted Runs:

Finished 121

122

123

124

still running at 3.98 MeV/u

19:08

S2-1 had tripped off due to leakge current going above 8uA

Camera watching leakages had also frozen so didn't realize until we checked downstairs

asked to lower beam intensity down to 55epA (was 120epA) @ run119

23:22

asked to set beam intensity to 100epA

upper limit of leakage set to 20uA

S2-1 leakage current ~9.93uA

Sorted Runs:

run120

run121 still running

At approximately 7pm, noted that trigger rate in S2-1 had dropped by factor of ~20. Detector had tripped off due to leakage current reaching 8uA - spotting this was delayed as camera (or web-browser) monitoring currents had frozen. Current trip point has been increased to 12uA, and the beam intensity lowered to try to preserve the detector through out the night.

At some point this may be increased again but that will have to await a discussion of how much the detector can take. Replacing it would take ~6hrs so ideally we'd like it to survive until the end of the experiment.

For the time being we need to monitor the leakage closely (and ensure the web cam image is updating) and if the trip point is approached, either lower the beam current or switch off the detector for a while to allow it to recover, or both.