2013/08/22

Attendees: Chagani, Kennedy, Mandic, Medved, Monin, Rogers, Villano.

Villano

1. Translation of OZIP to IZIP format raw data files.
   • Zhang's translation code has been successfully tested on OZIP raw data files.
   • Intend to run new data files through cdmsbats in the near future to check.
   • Will analyse old IZIP data first as mask exists for algorithms.
   • Once successful, 100 mm IZIP mask shall be added next.
   • Must determine what run properties we wish to write from the DAQ to the raw data files.
2. Data reduction, online data quality monitor and data backup through SLAC.
   • Working with Anders and Peter to make this a reality.
   • Successfully compiled cdmsbats on SLAC machines.
   • Difficult to determine how many times data would have to be reprocessed. Currently, little reprocessing is done. However, with improvements in the reduction code it is possible that reprocessing would be a more frequent occurrence in the future.
   • Creation of online plots of PSDs from filter files generated from raw data files that have been reduced on SLAC farm would be a good starting place.
   • Following this, a ROOT macro can be created to quickly analyse data from reduced files and spit out histograms that can be written to a ROOT file. These histograms can then be displayed in an online monitor too.
   • Copying data to SLAC kills two birds with one stone as it allows any member of the collaboration to access the data taken with K100 fridge.
   • Must determine an easy way to copy data from DAQ machine to SLAC farm.

Monin

• Template generation is relatively easy. However, trouble lies in finding events where all pulses look good for purposes of relative calibration.
• Additionally, pulses can only be selected from the first 6000 events or so as computer freezes past this point. Sounds like a memory leak.
• Must determine if this is indeed due to a memory leak and ensure that the entire data series can be utilised for the purpose of phonon pulse template generation.
• Possibility of using events which include some good phonon pulses was floated. This should increase number of statistics as there do not appear to be a sufficient number of events where all phonon pulses look decent.
• Abandoning the pulse selection algorithm and browsing through pulses by eye may lead to better statistics.

Chagani for Farinella

• Ben has added ability to extract pulses to BatViewer, both by eye and specifying event numbers in text file. Jeff has sent detailed pulse template generation instructions.
• Using G102a (100 mm 4Q device) data, pulse and crosstalk templates for each channel will be generated by selecting events that crop up in 356 keV peak.
• It is hoped to define 4Q device as new detector in cdmsbats. With this, comparisons between post-processing and optimal filter crosstalk corrections can be made.
• However, even if this is not achieved, having a technique available to quickly generate charge pulse templates would be very useful when reducing data series in the future.
• Hope to have completed set of templates for Q1 by next week.

Chagani

• A base temperature of 87 mK has been achieved this run.
• Turning on the still heater also results in a warmer still and mixing chamber, but colder cold plate. Adding more mixture to the fridge results in a colder cold plate, but warmer still and mixing chamber.
• Even though the still pressure is rather low, it does not appear to be running dry. If it was running dry, then the cold plate should also warm up with the still heater on as the warm mixture passing through the still heat exchanger from the condenser would not be immersed in the liquid mixture within the still. As a result, less heat would be transferred from incoming mixture to the mixture in the still, and therefore warmer mixture would arrive at the cold plate.
• The mixing chamber temperature increases with still temperature. However, the circulation rate increases with still temperature, making the cold plate colder. If anything the mixing chamber temperature should decrease with both a higher circulation rate and the cooler He-3 entering it from the cold plate. It looks very likely that there is thermal contact between the still and mixing chamber, and the most likely culprit is the 600 mK rod.
• Intend to conduct single shot test to measure He-3 concentration in mixture.
• Intend to attempt to save run by running still a little drier to cool it down. Unlikely to work.
• If aforementioned plan does not work, plan to warm up to room temperature, uninstall the tower, remove the 600 mK rod and cool down with an empty fridge. If the 600 mK rod is to blame then heating the still to provide a higher circulation rate should cool the mixing chamber.
• During next run with empty fridge, Kennedy to make changes to 600 mK rod such as adding polyethylene spacers in an attempt to prevent contact between 30 mK and 600 mK stages.
• During conversation with Nader earlier today, ionisation measurements from G106a would prove useful for comparison with charge collection efficiency study on MZIPs at Berkeley. No matter what base temperature is reached, these measurements will be performed before warm up. With a spot of luck, hope to have results by DTC meeting on 26th August.