Summary: The bias on the PMT was turned to its
maximum safe value of 1500 V for maximum gain.
There is a bit of a voltage drop in the PMT base between supply voltage
and the anode voltage, so at 1500 V supply voltage, we’re still not running at
the maximum rated cathode to anode voltage of 1500 V. Using peaks from several sources, a channel
vs. energy graph was constructed.
Although some of the peaks have small counts and need to be measured
more accurately, the linearity looks good with a resolution of about 188 V per
channel and a maximum detectable energy of about 203 keV.
If you're new to the experiment, scroll to the bottom for background information.
Data and Channel vs. Energy Mapping
Bias
|
1500 V
|
Gate Window
|
0.5 uS
|
Threshold
|
1.5mV
|
Attenuation
|
0 dB
|
Data set
|
HBC_00011
|
Source
|
Am 241 Taped to window
|
Start Time
|
~ 11:17 AM
|
Stop Time
|
~~ 1:30 PM
|
Date
|
2014_08_19
|
x-y scope V/div
|
1, 0.5
|
Shielded?
|
Yes
|
Tube
|
Harshaw B-
|
Spectrum Data
Bias
|
1500 V
|
Gate Window
|
0.5 uS
|
Threshold
|
1.5mV
|
Attenuation
|
0 dB
|
Data set
|
HBC_00012
|
Source
|
Cd 109 Taped to window
|
Start Time
|
2:18 PM
|
Stop Time
|
2:50 PM
|
Date
|
2014_08_19
|
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_00013
|
Source
|
Background
|
Start Time
|
2:56 PM
|
Stop Time
|
3:37 PM
|
Date
|
2014_08_19
|
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_00014
|
Source
|
Cs 137 Taped to window
|
Start Time
|
3:35 PM
|
Stop Time
|
3:59 PM
|
Date
|
2014_08_19
|
x-y scope V/div
|
1, 0.5
|
Shielded?
|
Yes
|
Tube
|
Harshaw B-
|
This run needs to be much longer to get more reliable
statistics. The run today was a short
one to get a ballpark picture of the detector’s channel vs. energy behavior
Channel Mapping
Using the peaks location from the three sources listed
above, Am 241, Cd 109, and Cs 137, the response of the detector with respect to
energy was mapped out.
The data for the peak locations is shown in the table below
Source
|
Peak Channel
|
Energy eV
|
Cd109
|
55
|
22100
|
am241
|
86
|
26344
|
Cs 127
|
104
|
32000
|
Am241
|
262
|
59541
|
Cd109
|
406
|
88000
|
|
1023
|
203390.39
|
The last row is a calculation using the least squares
regression fit parameters to determine the maximum energy that can be detected.
The peak energies vs. channel are shown in the following
graph.
Background
Hirsch's theory of hole superconductivity proposes a new
BCS-compatible model of Cooper pair formation when superconducting materials
phase transition from their normal to their superconducting state[1]. One
of the experimentally verifiable predictions of his theory is that when a
superconductor rapidly transitions, (quenches), back to its normal state, it
will emit x-rays, (colloquially referred to here as H-rays because it's
Hirsch's theory).
A superconductor can be rapidly transitioned back to its normal state by placing it in a strong magnetic field. My experiment will look for H-rays emitted by both a Pb and a YBCO superconductor when it is quenched by a strong magnetic field.
A superconductor can be rapidly transitioned back to its normal state by placing it in a strong magnetic field. My experiment will look for H-rays emitted by both a Pb and a YBCO superconductor when it is quenched by a strong magnetic field.
This series of articles chronicles both the experimental lab
work and the theory work that’s going into completing the experiment.
The lab book entries in this series detail the preparation and execution of this experiment… mostly. I also have a few theory projects involving special relativity and quantum field theory. Occasionally, they appear in these pages.
The lab book entries in this series detail the preparation and execution of this experiment… mostly. I also have a few theory projects involving special relativity and quantum field theory. Occasionally, they appear in these pages.
Call for Input
If you have any ideas, questions, or comments, they're very
welcome!
References
1. Hirsch, J. E.,
“Pair production and ionizing radiation from superconductors”, http://arxiv.org/abs/cond-mat/0508529
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