MIL-PRF-49319A(CR)
all elements of the Detector-Dewar shall have no noise peaks above the white noise reference value
greater than 8 dB from 300 to 10,000 Hz, and 12 dB from 10,001 to 20,000 Hz. using a 191 Hz,
Bandwith, Flat Top window. Vibration excitation shall be measured by an accelerometer mounted
on the mounting plate of the Detector-Dewar. The white noise reference level may be determined
by averaging the noise in each channel from 12,000 to 20,000 Hz with vibration applied. Noise
spectra shall be measured using a bandwidth between 50 Hz and 365 Hz.
3.5.14.1 Microphonics Vibration. The Detector-Dewar shall be coupled to a mechanical
cryogenic refrigerator that produces random vibrational excitation of the Detector-Dewar in three
mutually perpendicular axes. The frequency distribution of the vibrations shall be in a range from 0
to 20,000 Hz. The rms sum of the three axis vibrations shall be at least 1.0 g rms. Each axis shall
produce a minimum vibrational excitation of 0.4 g rms. In the frequency range of 2,000 to 20,000
Hz, the rms sum shall be at least 0.8 g rms.
3.5.15 Apparent thermal mass (cooldown). When mated to a cryogenic cooler capable of
cooling a test mass of 1.25 grams (250 joules) of aluminum (Figure 3) from ambient (296 K) to
80 K in not less than 5 nor greater than 6 minutes, the Detector-Dewar cooldown time from
ambient temperature to 80 K shall not exceed the time achieved with the test mass. This
measurement shall be made using a highly polished metal Detector-Dewar without any radiation
shielding. This test Detector-Dewar and test mass shall consist of the following: A high vacuum of
less than 10 microtorr, and a 1.25 gram aluminum test mass, (see B2-2303020104 paragraph 4.2.1).
The time to cool the thermal mass shall be recorded. The voltage output of the temperature sensor
diodes in the Detector-Dewar under test shall be measured at 77 ±1 K and at ambient temperature.
The voltage output at 80 K shall then be interpolated. The cooler shall then be coupled to the
Detector-Dewar using thermal grease and bellows. Operating bias power shall be applied and the
time for the temperature of the diode to reach 80 K shall be recorded.
3.6 Environmental conditions.
3.6.1 Temperature shock. The Detector-Dewar shall not be damaged (see 3.12.6) by sudden
changes in temperature between -54 C and +71 C (see 4.5.1 ).
3.6.2 High temperature. The Detector-Dewar shall not be damaged by storage or operation to
71°C (see 3.5.2).
3.6.3 Low temperature. The Detector-Dewar shall not be damaged by operation to -54 C or
storage to -62°C.
3.6.4 Shock. The Detector-Dewar shall not be damaged by high intensity shocks of 100 g's
peak amplitude with 11 milliseconds duration and by bench handling tests.
3.6.5 Vibration. The Detector-Dewar shall not be damaged by vibration over the frequency
spectrum at the specified g levels and amplitudes shown in Figure 1.
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