Pump downs
Date of pump down
Components
Reason
05/2021
X-Cooler and Poptop
Detector had not been used in years.
07/20/2022
Poptop
Detector temp increased (~5 degree increase in ~14 days, according to thermistor).
11/09/2022
Poptop
Detector resolution changed dramatically from 1.4KeV to 2.1KeV then to 5KeV with what looks to be double humped peaks.
Maintenance
Date
Components
Reason
Outcome
11/09/2022
X-Cooler II
Ortec sent new o-ring, sieve pill, and high vacuum grease to help try and remedy issues listed above under pumpdown for 11/09/2022.
11/10/2022
Poptop
Detector thermal contacts were cleaned using small amount of acetone and q-tips. Left to air dry before reassembly. Old sieve pill looks discolored but will be saved and stored as they can be refurbished via baking at IAC.
How to Read HPGe Thermistor Make sure detector high voltage is turned off
Unplug (or turn off) pre-amp power
Unscrew detector electronics housing (8 screws total)
Arrows pointing to screws on detector electronics housing Slide electronics housing towards the crystal end of the detector
Slide the sectioned area in the direction of the arrow to expose the thermistor terminals Turn multimeter to resistance (Ω) setting
Measure resistance across the white/black wires that exit the white nylon 4 pinned terminal
Check resistance in tables below for corresponding detector temperature
Resistance and Corresponding Temperatures 100-109Ω
Thermistor Resistance (Ω)
Detector Temperature (Κ)
100
76.5780
101
77.0421
102
77.5063
103
77.9706
104
78.4352
105
78.9000
106
79.3649
107
79.8300
108
80.2952
109
80.7607
110-119Ω
Thermistor Resistance (Ω)
Detector Temperature (Κ)
110
81.2263
111
81.6921
112
82.1581
113
82.6242
114
83.0906
115
83.5571
116
84.0238
117
84.4906
118
84.9576
119
85.4248
120-129Ω
Thermistor Resistance (Ω)
Detector Temperature (Κ)
120
85.8922
121
86.3597
122
86.8275
123
87.2954
124
87.7634
125
88.2317
126
88.7001
127
89.1686
128
89.6374
129
90.1063
130-139Ω
Thermistor Resistance (Ω)
Detector Temperature (Κ)
130
90.5754
131
91.0446
132
91.5141
133
91.9837
134
92.4524
135
92.9234
136
93.3935
137
93.8637
138
94.3342
139
94.8048
140-149Ω
Thermistor Resistance (Ω)
Detector Temperature (Κ)
140
95.2755
141
95.7465
142
96.2176
143
96.6888
144
97.1603
145
97.6319
146
98.1036
147
98.5756
148
99.0477
149
99.5199
150-159Ω
Thermistor Resistance (Ω)
Detector Temperature (Κ)
150
99.9923
151
100.4649
152
100.9377
153
101.4106
154
101.8836
155
102.3569
156
102.8303
157
103.3038
158
103.7775
159
104.2514
160-169Ω
Thermistor Resistance (Ω)
Detector Temperature (Κ)
160
104.7254
161
105.1996
162
105.6740
163
106.1485
164
106.6232
165
107.0980
166
107.5730
167
108.0482
168
108.5235
169
108.9989
170-179Ω
Thermistor Resistance (Ω)
Detector Temperature (Κ)
170
109.4746
171
109.9503
172
110.4263
173
110.9024
174
111.3786
175
111.8550
176
112.3316
177
112.8083
178
113.2851
179
113.7622
180-189Ω
Thermistor Resistance (Ω)
Detector Temperature (Κ)
180
114.2393
181
114.7167
182
115.1941
183
115.6718
184
116.1496
185
116.6275
186
117.1056
187
117.5838
188
118.0622
189
118.5408
190-199Ω
Thermistor Resistance (Ω)
Detector Temperature (Κ)
190
119.0194
191
119.4983
192
119.9773
193
120.4564
194
120.9357
195
121.4152
196
121.8947
197
122.3745
198
122.8544
199
123.3344
Thermistor Reading Log
Date
Time
Thermistor Measurement (Ω)
Detector Thermal Cycled Between Previous Measurement
Notes
04/13/22
11:45am
241.2
Yes
Detector casing cold to touch, has been cooling down >72hrs
04/13/22
1:50pm
229.3
No
04/14/22
11:26am
176.0
No
06/02/22
11:46am
185.0
No
Cooler was off for a few minutes prior due to detector being moved to other side of room
06/16/22
10:00am
176.8
No
Measured before use of high voltage
06/30/22
11:00am
184.1
No
Shutdown cable measurement of -11.97, change from normal of -11.87V
07/03/22
12:45pm
182.2
No
07/06/22
11:40am
181.7
No
Detector warmed after this measurement in prep for pumpdown
07/21/22
10:50am
177.2
Yes
Poptop pumped down by IAC, chiller turned on 3:50pm 07/20/22
07/21/22
11:00am
176.2
No
Repeat of above
07/21/22
11:30am
174.7
No
Repeat of above
07/21/22
12:30pm
173.4
No
Repeat of above
07/21/22
1:22pm
172.0
No
Repeat of above
07/21/22
2:11pm
171.2
No
Repeat of above
07/21/22
3:30pm
170.3
No
Repeat of above
07/25/22
10:10am
169.5
No
Detector continued to cool over a weekend, shutdown cable = -11.99V
10/27/22
10:55am
181.2
No
Resolution of detector changed from ~1.4KeV FWHM to ~2.1KeV FWHM
11/01/22
10:48am
171.8
Yes
Thermal cycle of detector in attempt to bring temp back down, attempt was successful.
11/03/22
12:16pm
175.1
No
Cs137 peak was wide, poor energy resolution. HV/Preamp turned off, detector beginning to cool again.
11/03/22
1:00pm
170.8
No
Preamp & HV off for 45 mins, detector cooled again.
11/06/22
12:58pm
184.2
Yes
Thermal cycled detector due to >5KeV sigma in energy peaks.
11/07/22
7:45am
192.6
No
Detector cooling for >36hrs
PAS HPGe Detector
