Thursday, August 21, 2014

Magnet Water Flow Good and Channels Linear: Lab Book 2014_08_20

Summary:  Longer spectrum runs were performed on each of the available low energy sources.  The channel vs. energy graph was re-plotted based on the new data.  The behavior is still linear.  The only issue at the moment, is that the signal levels are close to the noise count levels, causing the peaks from each of the sources to be fairly broad.  This should be OK.  since we're just looking for evidence of a signal at all, resolution won't be critical in this application.  The iron magnet cooling supply was completely installed and can supply two gallons per minute to the magnet, meeting the specification.  A Cs 137 Dewar attenuation spectrum was started.  The data will be collected on the morning of the 21st.

Bias
1500 V
Gate Window
0.5 uS
Threshold
1.5mV
Attenuation
0 dB
Data set
HBC_00015
Source
Cs 137 Taped to window
Start Time
8:53 AM
Stop Time
11:58 AM
Date
2014_08_20
x-y scope V/div
1, 0.5
Shielded?
Yes
Tube
Harshaw B-







Bias
1500 V
Gate Window
0.5 uS
Threshold
1.5mV
Attenuation
0 dB
Data set
HBC_00016
Source
Cd 109 Taped to window
Start Time
12:15 PM
Stop Time
1:38 PM
Date
2014_08_20
x-y scope V/div
1, 0.5
Shielded?
Yes
Tube
Harshaw B-




Bias
1500 V
Gate Window
0.5 uS
Threshold
1.5mV
Attenuation
0 dB
Data set
HBC_00017
Source
Am 241 Taped to window
Start Time
2:01 PM
Stop Time
6:41 PM
Date
2014_08_20
x-y scope V/div
1, 0.5
Shielded?
Yes
Tube
Harshaw B-








Channel Linearity


Source
Peak Channel
Energy eV
Cd109
59
22100
am241
95
26344
Cs 137
108
32000
Am241
271
59541
Cd109
421
88000

1023
197523.88

Magnet Cooling
To cool the magnet properly,  a water flow of two gallons per minute is required.  That corresponds to 3.785 liters every 30 seconds.  3.75+ liters was measured into a bucket, and a piece of tape was placed with its lower edge at the water level.  Flow speed trials were run by watching the water level compared to the tape in 30 second intervals.  The required flow rate was achieved after several incremental water flow increases at the sink.  The flow can be measured at the sink, but as a ball park indictor, the “CW” indicator should be readable from left to right and perched at about 30 degrees to the horizontal.
There were initially leaks at the right most input manifold and at the garden hose output manifold.  There is still a leak at the sink fitting.  A weight has been placed on top of the hose to hold it in the sink so the leak flows down the drain rather than down the cabinet.



Signal Attenuation Due to Dewar
The material that makes up the liquid helium Dewar will attenuate the signal form the experiment.  The level of attenuation is being measured by collecting count data on each of the sources inside and outside the Dewar.  The setup for the Dewar attenuation runs is shown below.  The source was lowered into the sample chamber of the Dewar on the end of a wooden yard stick  It was taped in place with a thin layer of paper, (to protect the source from the tape), and two layers of electrical tape.  The yard stick was roughly centered in the chamber with two rolls of masking tape as shown below.





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