The neutron sensitivity of film is considered to consist of two components, a response to lowenergy (thermal) neutrons, and a response to high-energy neutrons. As far as could be determined from the experiment, the two components were independent and additive. The calibration
data for neutron flux was furnished AFSWC by N-2 division at LASL.
TABLE 2.5
It was assumed that any
FILM SENSITIVITY TO NEUTRONS
See Section 2.3.1 for source of data.
DuPont
Packet
Low Energy (Gold)
Film
Type
Neutrons
High Energy Neutron
Dose
(n/om’) r x 107?
606
12990
606
510
502
n rep dose/r
606-1290
606-1250
553
4.7 + 2.4
3.9 + 2.2
3.44 1.8
37 + 22
3h + 20
28417
553
553
2.9% 1.4
3.2 41.7
19412
26415
perturbation in flux caused by the NBS film holders would be small.
Neutron-sensitivity values
were compared to the amount of Co"? gamma radiation required to produce the same optical den-~
sity. Table 2.5 summarizes the data obtained.
For all shots except Cherokee, the relative air densities were 0.895 + .002. For Cherokee
it was 0.847; however, the data were adjusted to a relative air density of 0.895 to permit comparison of results. No air-density adjustment was made for the other events.
In analyzing the initial data to determine the flux that existed outside the station, it was im-
portant to take into account the attenuation offered by the station and the instrumentation inside.
Table 2.6 presents a list of station types and calculated shielding correction factors based on a
3.5-Mev gamma energy in accordance with the assumptions of Reference 25. A mutual instrument-shielding correction factor for each station type was estimated and is given in Table 2.6.
TABLE 2.6
INITIAL-GAMMA-EXPOSURE CORRECTION FACTORS
Station Series
Station
am
Shielding
Mutual
or
Shielding
Combined Quartz
Fiber and Chemica!
.
Correction Factor
Betatron Film
a
Normalization
Combined Film
.
Correction Factor
210
210! without quartz
1.05
1.05
1.10
0.90
1.0
211
fiber rate
212 device
1.35
1.10
1.48
0.90
1.35 + 0.10
211 fiber rate
212 device
1.40
1.15
1.61
0.90
1.45 + 0.10
213
1.20
1.05
1.26
0.90
1.15 + 0.05
113
4.15
1.05
1.21
0.90
1.10 + 0.05
40.05
210’ with quartz
An experimentally determined film betatron calibration factor of 0.9 is also listed. The combined correction factors were computed from the above-mentioned factors. The betatron calibration factor applied to the film only. No betatron calibration data were available for the quartz
fiber and chemical dosimeters, and a factor of 1.0 was assumed.
23