ENTRY            M0675   20050906
SUBENT        M0675001   20050906                                 
BIB                 15         43                                 
TITLE      Photoneutron cross  section  measurements  on   186W,  
            187Re and 188Os for cosmocronology.                   
CRITIQUE   The 188Os data are published only  (as  mentioned  in  
            Abstract).                                            
AUTHOR     (T.SHIZUMA,H.UTSUNOMIYA,S.GOKO,P.MOHR,T.HAYAKAWA,      
           A.MAKINAGA,K.Y.HARA,H.OHGAKI,Y.-W.LUI,S.GORIELY)       
REFERENCE  (J,NP/A,758,561,2005)                                  
INSTITUTE  (2JPNJAE,2JPNKON,2GERTHD,2JPNKTO,1USATAM)              
FACILITY   (ESTRG,2JPNAIS) Electron storage ring TERAS at the     
            National Institute  of Advanced Industrial  Science   
            and Technology (AIST).                                
INC-SOURCE (QMPH,COMPT) Quasimonochromatic     Laser     Compton  
            scattering (LCS)  g-ray  beam  with  typical  energy  
            resolution of 10 % FWHM.                              
DETECTOR   (PROPC) 3He proportional counters.                     
METHOD     (RINGR) 16 3He  proportional  counters  embeded  in a  
            polyethilene moderator  cube  in  double  concentric  
            (inner (7  cm distance from beam axis) and outer (10  
            cm distance  from  beam  axis))  rings;  ring  ratio  
            between neutron  counts  of  the  inner  and   outer  
            counters  was  used to determine the average neutron  
            energy.                                               
SAMPLE     Metallic powders of 186W, 187Re and 188Os enriched to  
            99.79,  99.5 and 95.0 %,  respectively, were pressed  
            to self-supporting tablets with a diameter of 8 mm.   
ANALYSIS   Direct measurement.                                    
ERR-ANALYS Statistical errors.                                    
COMMENT    Cross sections of the 186W,187Re,188Os(g,n) reactions  
            were measured using quasimonochromatic  g-ray  beams  
            from laser Compton scattering (LCS), and results for  
            the latter reaction are presented.  Neutron  capture  
            cross sections   of   the   inverse  reactions  were  
            evaluated by    the    Hauser-Feshbach   statistical  
            calculation where the experimantal data were used to  
            constrain the model parameters, especially by the E1  
            strength function.  The  influence  of  the  neutron  
            capture by the 9.75 keV first excited state in 187Os  
            which is substantially populated in stellar  plasmas  
            at typical  s-process  temperatures  is  examined in  
            connection with the 187Re - 187Os cosmocronology.     
STATUS     (CURVE) The data from Fig.  1 have been digitized  at  
            the Russia MSU SINP CDFE by V.V.Varlamov.             
HISTORY    (20050901C)                                            
ENDBIB              43                                            
NOCOMMON                                                          
ENDSUBENT           46