Dieter Best has completed an impressive study of the trigger bias for the
E895 experiment. His study has used a far larger data sample than that
used in the UCD analyses. The table below shows the comparison of the
effective trigger cross sections determined in the Best study to those
determined in the UCD studies. The directly measured quantity was the
ratio of the number of Interaction triggers to the total number of beam
particles. To convert this number to cross section, one must divide this
number by a target related normalization constant which is determined by
multiplying the density times the target thickness times Avagodro's
number divided by the atomic weight.
Trigger Type
Target
Ratio
Sigma(trig)
(barns)
UCD Sigma
(barns)
Targ. Rel
UCD TR%
2 AGeV
Central
2%
.0072
2.46
N.A.
2 AGeV
Min. Bias
2%
.0097
3.31
3.33
66%
62%
4 AGeV
Central
1%
.0037
2.52
2.62
56%
71%
4 AGeV
Min. Bias
6 AGeV
Central
3%
.0049
1.11
0.78
6 AGeV
Min. Bias
3%
.0327
7.43
7.45
41%
N.A.
8 AGeV
Central
3%
.0019
0.43
0.50
8 AGeV
Min. Bias
3%
.0218
4.95
5.29
48%
54%
Note: The measured total reaction cross section for Au+Au at 10.6 AGeV is
6.78 barns. The geometric cross section for two gold nuclei of radius 7.1
fm would be 6.33 barns.