Results of flux and radiation dose calculation based on pythia (pp200) and hijing (pAu 200 and p Al 200) and  GEANT3+GCALOR for STAR geometry y2015 are summirized on  

http://www.usatlas.bnl.gov/~fisyak/star/Flux/2015/

For normalization were used James Dunlop estimation for integrated luminosity

06/19/2015 ===================
Ok, so this is tagged on "physics on", fully singles corrected ZDC coincidence rate
pp:
http://www.star.bnl.gov/protected/common/common2015/trigger2015/sampleEfficiencypp200GeV/integrated_delivered_byfill_time.png
using cross section 0.264e9 ;(pb) #ZDC from van der Meer scan,

pAu:
http://www.star.bnl.gov/protected/common/common2015/trigger2015/sampleEfficiencypAu200GeV/integrated_delivered_byfill_time.png
using cross section 35e6 nb

pAl:
http://www.star.bnl.gov/protected/common/common2015/trigger2015/sampleEfficiencypAl200GeV/integrated_delivered_byfill_time.png
using cross section 11.4e6 nb;

and his estimation of cross sections

06/24/15 ====================

BBC cross section is something like 50x the trigger version of the ZDC coincidence,
which has cross section 11.4/1.68/0.96 = 7 mb, i.e.
http://www.star.bnl.gov/protected/common/common2015/trigger2015/plots_pAl200gev/plots.html#BBCMB
i.e. 0.35 b

Cross-check:
For the pAu, BBC cross section is something like 80x the trigger version of the ZDC coincidence,
which has cross section 35/1.68 = 21 mb, i.e. 1.6 b

Checking scaling, should go roughly like A^(2/3), so 
1.6 b/(197^{2/3})* (27^{2/3}) = 0.43 b, bit high.
Alternatively, as an estimate 40 mb * 27^{2./3.} = 0.36 b, pretty close.

The 1.6b for p+Au might be an overestimate due to backgrounds, because the BBC/ZDC shows a lot of structure.
I think Glauber gives something closer to 1.5 b.

BBC should be sensitive to most of the inelastic cross section.  So something like 0.35 b should be close
for the inelastic cross section for p+Al.