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 deter-
mined 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. It was assumedthat any
TABLE 2.5
FILM SENSITIVITY TO NEUTRONS
See Section 2.3.1 for source of data.
DuPont
Film
Packet °
Type
606
1290
606
510
502
606-1290
606-1250
553
553
553
Low Energy (Gold)
Neutrons
High Energy Neutron
Dose
(n/em’) r x 1073
n rep dose/r
4.74
3.9 +
3.44
2.34
3.24
2.4
2.2
1.8
1.4
1.7
37 + 22
31 + 20
28 +17
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 density. 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 important 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
210
Station
as
Shielding
Mutual
aa
Shielding
Combined Quartz
.
.
Fiber and Chemical
,
Correction Factor
Betatron Film
as
Normalization
Combined Film
.
Correction Factor
210' without quartz
.
1.05
.
1.05
.
1.10
‘
0.90
0
£0.
1.0
0.05
211
fiber rate
212 device
1.35
1.10
1.48
0.90
1.35 + 0.10
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
118
1.15
1.05
1.21
0.90
1.10 + 0.05
210' with quartz
211 fiber rate
212 device
An experimentally determined film betatron calibration factor of 0.9 is also listed. The com-
bined 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