*
cedars oh hak
6
wn Unk
NRL REPO RT 6374
TABLE 3
Calculated 8 Counts Obtainable From 20-Minute Collections of Radon Daughters on Glass
Fiber Filters for a Radon Concentration of 100 pCi/m' and a Filtration Rate of | m*/min
ar the
| fol-
Disintegrations
During 10-Minute
x 100
in at
Periods
3 for
it 61
fii
for
p= 0.048
rber
vals
the
| as
RaB
RaC
Total
Ratio
(tet-71/t1-11)
ited
ods
p= 0.190
uct
otal
RaB
Rac
Total
Ratio
(te1-71/f1-11)
BOURSESarn:
p = 0.390
RaB
RaC
Total
Ratio
(te1-71/t1-11)
p = 0.564
RaB
RaC
Total
Ratio
(tga-71/£1-11)
p= 0.735
RaB
RaC
Total
Ratio
(te1-71/t1-11)
tev
3798
1687
5485
864
1594
2458
0.448
13170)
8233
21403
2879
5640
8519
0.398
22700
19562
42962
4903
10279
15182
0.359
28946
30758
59704
6227
13775
20002
0.335
33221!
41689
74910
7136
16562
23698
0.316
Total Counts During 10-Minute Periods
No Absorber
faut
61-71
518]
244)
762
118
231
349
0.458
1795
1192]
2987
392
817
1209
0.405
30941
2833
5927
668
1488
2156
0.364
3945]
4454
8399
849
1995
2844
0.339
4528). 973
6037 2398
10565 3371
0.319
the true values. With no absorption except for
that inherent in the counting tube window, maxi-
mum count rates are obtained but also decreased
sensitivity results because both RaB and RaC
are counted simultaneously; moreover, the
effect of the large quantity of low-energy conver-
sion electrons associated with RaB cannot be
accurately assessed. Since a 10-mil aluminum
absorber will remove nearly all response to the
conversion electrons from the RaB and_ also
5-mil Absorber
fee
fe1-71
171
180
35]
39
170
209
0.595
594]
879
1473
130
602
732
0,497
1024
2089
3113
291
1098
1319
0.424
1305]
3285
4590
281
1471
1752
0.382
1498
445?
5950
322
1769
2091
0.351
10-mil Absorber
fia
f61-71
71
137
208]
16
130
146
0.702
246
670
916}
54
459
513
0.560
494
1592
2016
92
837
929
0.461
541
9504
3045
116
1121
1237
0.406
621
3393
4014;
133
1348
1481
0.369
30-mil Absorber
feu
0
54{
54]
£61-71
0
51
51
0.945
0
264
264
0
181
181
0.685
0
628
628
0
330
330
0.525
0
987
987
0
442
442
0.448
«0
1338
1338
0
532
532
0.397
reduce to a considerable extent the counter
response to the RaB itself, use of an absorber of
this 10-mil thickness is considered to be a practical
compromise.
Estimations of the overall errors (standard deviations) based on the counting statistics to be
expected from use of this procedure to determine
the radon concentration have been made for the
conditions of an air flow of 0.5 m/min, a back-
ground of 30 counts/min, and a 5% contribution