Gamma rays irradiation

Our experimental techniques have been described extensively in earlier papers (2, 13). The gamma ray irradiations were carried out in a 50,000-curie source located at the bottom of a pool. The photoionization experiments were carried out by krypton and argon resonance lamps of high purity. The krypton resonance lamp was provided with a CaF2 window which transmits only the 1236 A. (10 e.v.) line while the radiation from the argon resonance lamp passed through a thin ( 0.3 mm.) LiF window. In the latter case, the resonance lines at 1067 and 1048 A. are transmitted. The intensity of 1048-A. line was about 75% of that of the 1067-A. line. The number of ions produced in both the radiolysis and photoionization experiments was determined by measuring the saturation current across two electrodes. In the radiolysis, the outer wall of a cylindrical stainless steel reaction vessel served as a cathode while a centrally located rod was used as anode. The photoionization apparatus was provided with two parallel plate nickel electrodes which were located at equal distances from the window of the resonance lamp. 

R Kishi, O Hirasa, H Ichijo. Fast responsive poly(N-isopropylacrylamide) hydrogels prepared by gamma-ray irradiation. Polym Gels Networks 5 145-151, 1997. 

Bone 109Cd gamma-ray irradiation with source at 2.5 cm from skin of proximal tibia K-XRF 2 pg/g No data Hu et al. 1989, 1990, 1991... 

A review on individual monomers using gamma-rays irradiation, still by direct grafting of polyamides, is presented below. 

In a joint program conducted between PlcArsn and Brookhaven National Laboratory, Abel et al (Refs 49 63) studied the effect of reactor and gamma-ray irradiation on the impact sensitivity of colloidal Pb azide. With reactor irradiations ranging from 3.3 x 1017 to 1.57 x 1018nvt (n/cm2) (fast plus slow neutrons) and the accompanying reactor gamma dose rate of 2 x 106R/hr the effects are shown in Fig 4. The results indicate that there is a definite increase in the impact sensitivity of colloidal Pb azide as a function of total neutron dose. The studies... 

Herley, Levy and co-workers (Refs 208, 211, 224, 228, 240, 241, 244, 255 258) have subjected AP in all forms to various types of radiation. AP in small and large crystal form, powder, and powder-A1 mlxts have been exposed to gamma rays, X-rays, fast neutrons, and fast neutrons followed by a gamma-ray irradiation. 

A search of the literature has revealed that the amount of work related to the pulsed gamma-ray irradiation of proplnts and propulsion components has been minimal. Usually the gamma component in pulsed reactor irradiations are the values considered, but practically no work has been done on pulsed gamma-ray effects... 

Oxygen Taliani Test of Gamma-Irradiated Propellants ARP, AHH, and CDT , NPP-TMR-172, Naval Propint Plant, Indian Head (1959) 78) E.S. Freeman et al, The Effects of X-Ray and Gamma Ray Irradiation on the Thermal Decomposition of Ammonium Perchlorate in the Solid State , JPhysChem 64, 1727 (1960) also PATR 2673 (1960) 79) G. Todd E. Parry,... 

Mapes et al, Effects of Gamma-Ray Irradiations on Five Plastic-Coated High Explosive Compositions , TID-15426, Brookhaven Natl Lab, Upton... 

Thermal Decomposition of Ammonium Perchlorate During Gamma-Ray Irradiation , Defense Nuclear Agency Rept DNA 4032P-3,... 

When ground beef is irradiated by electron beam and gamma-ray irradiation and its proteins assayed for amino acid content, the most sensitive amino acid to irradiation by either source is cystine. Approximately 50% of cystine is destroyed under the most damaging conditions used. Under the same conditions tryptophan shows about 10% destruction while arginine, phenylalanine, and tyrosine showed no destruction, and the rest of the amino acids show little destruction. From the cystine and tryptophan data, it appears that for electron beam irradiation the extent of destruction is not related primarily to total dose but to dose rate and particularly to energy level of irradiating dose. 

The principal polyphosphazenes that have been used in hydrogels are those with linear or branched ethyleneoxy side chains, aryloxy groups with carboxylic acid substituents, or mixed-substituent polymers that bear hydrophilic methylamino side groups plus a hydrophobic cosubstituent such as phenoxy or trifluoroethoxy. Cross-linking is usually accomplished by gamma-ray irradiation or, in the case of the carboxylic acid functional species, by treatment with a di- or tri-valent cation. Here, we will consider another example based on MEEP (3.79), a polymer that is well suited to the clean method of radiation cross-linking. 

With cyclic amides, N-alkyl-caprolactams, the tendency was similar, namely no obvious change in the extraction of Th(IV) and U(VI) was observed in the range 102—104 Gy. But if the gamma-ray irradiation dose was higher than 104 Gy, >U(Vi, decreased with the increased dose, as observed for TBP. This effect was stronger when one radical on nitrogen was branched (2-ethylhexyl instead of n-octyl) (201). 

Tanizaki, Y., Maeno, T., Nakamura, M. and Yamazaki, M. (1996) Use of an ultrafiltration and gamma-ray irradiation technique for studying the speciation of trace elements in river waters./. Environ. Sci. Health, A31, 913-940. 

Research using gamma-ray irradiation at Seibersdorf has reported pseudo-first-order decomposition of TCE and PCE [17,18]. Flowever, a significant departure from pseudo-first-order kinetics was noted with the e-beam system. This may be due to dose rate effects (1890 Gy s 1 maximum vs. 1.5 Gy s 1 for 60Co), or due to nonuniform dose distribution, or a combination of both [52]. Fig. 6 shows the departure from first-order behavior seen when the e-beam system is used as the source for the irradiation of drinking water containing TCE. 

Figure 1 shows electrical conductivity measured at 300 K in air, after gamma-ray irradiation at the several doses up to around 170 kGy. The line described in Fig. 1 shows linear function expressed as a = 4xl0 8 D + 10"8. Flere, a is the conductivity and D is absorption dose of the samples. So the conductivity increased with increasing the absorption dose in linear form. The conductivity at 170 kGy was higher by about three orders of magnitude than that of unirradiated one. 

Figure 1. Electrical conductivity at 300 K as a function of absorption dose by gamma-ray irradiation.

The optical absorption of the unirradiated and irradiated samples was measured. The spectrum of unirradiated sample has two peaks at 200 and 275 mn. The intensity absorption of ultraviolet region increased with increasing the dose and new absorption band was observed at 215 nm after gamma-ray irradiation. The optical densities normalized by that of unirradiated sample as shown in Fig. 4. Several absorption peaks at 200, 215 and 275 nm were associated with fluorocarbon and peroxy radicals and C=0 groups respectively 131. The cross-linkage and chemical bond breaking of the polymer chain were caused by gamma-ray irradiation. 

Fig. 3. The relation between differential G-values of crosslinking in polystyrene resist films and stopping powers. The G-values for gamma-ray irradiation ( ) are from Ref. 34. The typical error is shown for 1.0 MeV H+ beams. From Ref. 3...

W3. Wang, S. M., Nishigori, C., Yagi, T., and Takebe, H., Reduced DNA repair in progeria cells and effects of gamma-ray irradiation on UV-induced unscheduled DNA synthesis in normal and progeria cells. Mutat. Res. 256, 59-66 (1991). 

Furusawa K, Terao K, Nagasawa N, Yoshii F, Kubota K, Dobashi T (2004) Nanometer-sized gelatin particles prepared by means of gamma-ray irradiation. Colloid Polym Sci 283(2) 229-233... 

Wang BL, Kodama M, Mukataka S, Kokufuta E (1998) On the intermolecular crosslinking of PVA chains in an aqueous solution by gamma-ray irradiation. Polym Gels Netw 6(1) 71—81... 

Khatri, R. Asoka-Kumar, P. Nielsen, B. Roellig, L.O. et al. (1993) Positron trap centers in X-ray and gamma-ray irradiated Si02 , Appl. Phys. Lett. 63, 385. 

Zhang, Z., Ito, Y. (1991) Microstructure of gamma-ray irradiated poly-ethylenes studied by positron annihilation . Radial. Phys. Chem. 38(2), 221. 

Figure 1. Dose dependence of the conductivity at 300 K in air for the gamma-ray irradiated perfluorosulfonic acid membranes.

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