Determination of narrow beam attenuation coefficients from a broad beam geometrical configuration for 320 keV photons

✍ Scribed by H.A. Jahagirdar; B. Hanumaiah; S.R. Thontadarya

• Publisher: Elsevier Science
• Year: 1992
• Weight: 443 KB
• Volume: 43
• Category: Article
• ISSN: 0883-2889
• DOI: 10.1016/0883-2889(92)90180-m

✦ Synopsis

Narrow beam mass attenuation coefficients, p/p, of 320 keV photons, emitted from the 5'Cr radioisotope have been measured in various high Z materials such as Pb; BiPO,; (CH,COO), Pb .3H,O; Pb(NO,),; Na,WO,.2H,O, using a broad beam geometrical configuration, employing a 2" x 1" (5.1 cm x 2.54 cm) (0.051 m x 0.025 m) NaI (Tl) detector spectrometer system coupled to a 1 k multichannel analyser. The measured p/p values in cm*/g for the above materials in the transmission range from 50% to 20% respectively are 0.34 & 0.01 (0.35); 0.295 f 0.002 (0.30); 0.23 + 0.01 (0.24); 0.256 f 0.003 (0.26); 0.255 f 0.003 (0.256). The values given in parentheses are estimated theoretically from the mixture rule using tabulated values of Hubbell (1982). It is observed that for high Z compounds at low energies, the exponential law of attenuation will be valid even for a broad beam set up in the transmission range from 50% to 20%. The attenuation coefficients of elements derived from this method agree fairly well with the tabulated narrow beam attenuation coefficients indicating the validity of the mixture rule in this region of transmission.