Those p a r t i c i p a t i n g i n t h e f i f t h Workshop prepared summary r e p o r t s o f t h e i r r e c e n t work f o r i n c l u s i o n i n t h i s document. The r e p o r t s a r e reproduced here as submitted by t h e p a r t i c i p a n t s . O f special i n t e r e s t a t t h i s meeting was t h e r e p o r t by t h e National Bureau o f Standards o f t h e a v a i l a b i l i t y o f new low energy monoenergetic neutron c a l i b r a t i o n f a c i l i t i e s . I n

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... w i t h ERDA, and p r i n c ip a l l y by t h e e f f o r t s o f t h e Workshop Chairman, E. J. V a l l a r i o , t h e N a t i o n a l Bureau o f Standards has equipped t h e i r r e a c t o r f a c i 1 i t y w i t h s p e c i a l p o r t s t o provide these h i g h p u r i t y neutron beams. By using a manganese s c a t t e r e r f o l l o w e d by a scandium f i l t e r , a h i g h p u r i t y beam of 2 keV neutrons i s obtained. By u s i n g a t i t a n i u m s c a t t e r e r followed by an i r o n f i l t e r , a monoenergetic beam o f 25 keV neutrons i s obtained. The 2 keV spectrum contains about 3 percent higher energy neutrons w h i l e 25 keV spectrum i s betcer than 99 percent a t t h e 25 keV energy l e v e l . By u s i n g t h e a v a i l a b l e scanner, b o t h beams can be appl i e d t o an e x p e r imental area measuring 18 x 25 inches. 5 A t 2 keV, 6.5 x 10 neutronslsec can be d e l i v e r e d t o the e x p e r i -6 mental area w h i l e f o r t h e 25 keV beam, 5 x 10 neutrons/sec can be d e l i v e r e d t o t h e experimental area. The a c t u a l dose r a t e s a r e a function of the experimental area scanned and the reactor operating power levels. For both of these beams, gamma radiation levels to a few rr~R per hour will also be present. Those participating in the conference were encouraged to make use of these special neutron f a c i l i t i e s for their neutron dosimetry research and development programs as well as special studies that could benefit from such irradiation. Work i s in progress a t National Bureau of Standards with a silicon f i l t e r t o develop a pure 144 keV neutron source. A thermal energy neu-5 9 tron beam of 5 x 10 to 10 neutrons/sec i s available. PERSONNEL NELITRON DOSIMETRY AT RADIATION PROTECTION BUREAU V. Balasubrahmanyam R a d i a t i o n P r o t e c t i o n Bureau Department o f Health and Welfare Ottawa, Canada Canada has a r e l a t i v e l y l a r g e National Dosimetry Service i n operat i o n s i n c e 1951. I n 1974 approximately 800,000 f i l n i s were processed and dosimetry s e r v i c e s were provided t o 50,000 people a t 7,000 organi zations. O f t h i s , neutron dosimetry services employing n u c l e a r emulsion f i l m dosimeters covered 1,500 people a t 65 o r g a n i z a t i o n s . During 1974 approximately 20,000 f i l m s were processed. F i f t y o r g a n i z a t i o n s were r e q u i r e d t o have neutron dosimetry services based on the e x i s t i n g Atomic Energy Control r e g u l a t i o n s . Nuclear emu1 s i o n f i l m dosimetry covers a dose range from about 50 mrem t o 8 rem. Pu-Be i s used as a standard source. Most o f t h e r e g u l a r neutron exposures were i n the range o f 0-100 mrem. For C r i ti c a l i t y a c c i d e n t monitoring, a c t i v a t i o n d e t e c t o r s (e.g., I n , S and Au) a r e employed. I t i s r e a l i z e d t h a t t h e o p e r a t i o n o f t h e Neutron Dosimetry Service i s time consuming because o f mechanical scanning o f t r a c k s through a microscope TV arrangement and i s prone t o e r r o r s o f several types. mate neutron dosimetry services, improve t h e accuracy o f neutron dosime t r y measurements and be compatible w i t h e x i s t i n g X, beta, gamma body dosimetry systems. I n t h i s context, some p r e l i m i n a r y work employing calcium sulphate ( t h u l i u m ) powder i n rubber m a t r i x has been c a r r i e d o u t ( ' ) and reported. This study revealed possi b i 1 i t i e s and a d d i t i o n a l developmental work t o increase t h e s e n s i t i v i t y i s being considered. Reference 1. Sui t a b i 1 i t y o f CaSO4:Trn Systems f o r Occupational Dosimetry, paper presented a t t h e F o u r t h I n t e r n a t i o n a l Conference on Luminescence b u t reproduci b i 1 i t y and neutron energy redponse are 1 ess than d e s i r a b l e ) ; (1 ) d e t e r m i n a t i o n o f t h e p r e c i s i o n and r e p r o d u c i b i l i t y o f f i s s i o n fragment spark c o u n t i n g under t h e p o i n t o f view o f developing m a i l a b l e t r a n s f e r dosimeters o f s u f f i c i e n t p r e c i s i o n (a < 5%) i n t h e %SO-500 r a d range ( i t was shown t h a t a r e p r o d u c i b i l i t y w i t h i n +3-5 percent i s p o s s i b l e b o t h w i t h spark and v i s u a l counting);(') and f e a s i b i l i t y of t r a c k spark counting i n mica. ( 3 ) We found t h a t t h e p e r f o r a t i o n s created a t t h e impact l o c a t i o n o f high-LET charged p a r t i c l e s such as f i s s i o n fragments i n t h i n sheets o f etched muscovite mica can a l s o be c o n v e n i e n t l y evaluated by spark counting. Ancient f i s s i o n t r a c k s i n t h e mica a r e annealed by an 800°C treatment. Mica o f f e r s advantages i n c e r t a i n a p p l i c a t i o n s as an i n o r g a n i c d e t e c t o r which can be e a s i l y scanned by n o n o p t i c a l means, because o f t h e h i g h thermal s t a b i l i t y o f t h e l a t e n t t r a c k s (>500°C) and e x c e l l e n t d i s c r i m i n a t i o n a g a i n s t low-LET p a r t i c l e s . I I n s t u d i e s r e g a r d i n g t h e r e l a t i o n s h i p between TSEE and TLD i n BeO, ( 4 i t was found t h a t t h e p h y s i c a l and chemical treatments a f f e c t i n g t h e * Research sponsored by t h e Energy Research and Development A d m i n i s t r a t i o n under c o n t r a c t w i t h Union Carbide Corporation. s e n s i t i v i t y and s t a b i l i t y o f TSEE e x e r t s i m i l a r e f f e c t s on t h e TLD performance. By measuring t h e TL i n t h e UV, t h e lower d e t e c t a b l e exposure l i m i t i s %1 mR. As t h e TL and TSEE peaks a r e w e l l separated, t h e penet r a t i n g r a d i a t i o n component i n a mixed f i e l d can, i n p r i n c i p l e , be evaluated by a TL (volume e f f e c t ) measurement, f o l l o w e d by measuring t h e nonpenetrating, surface dose i n t h e TSEE peak a t a h i g h e r 'temperature. The accuracy i n TSEE f a s t neutrons dosimetry has thus been improved because o n l y a s i n g l e d e t e c t o r , i n s t e a d o f t h e d e t e c t o r p a i r used i n previous s t u d i e s f o r d i s c r i m i n a t i o n between t h e gamma and neutron doses, i s r e q u i r e d . ( 5 ) There remain, however, problems w i t h regards t o t h e s t a b i 1 i t y and reproduci b i 1 i ty o f TSEE dosimeters. I n agreement w i t h c u r r e n t t h e o r i e s about t r a p s a t u r a t i o n processes along charged p a r t i c l e tracks, an increase o f t h e LET o f r a d i a t i o n cons i s t e n t l y produces a r e d u c t i o n i n t h e TL response o f conventional synt h e t i c phosphors based on LiF, CaF2, o r CaS04 as w e l l as i n some m i n e r a l s . The alpha t o gamma r a d i a t i o n response r a t i o on a rad/rad basis v a r i e s from phosphor t o phosphor, and o f t e n from peak t o peak i n the same phosphor, u s u a l l y between 0.05 and 0.5. There have, however, a l s o been r e p e a t e d l y claims by Russian researchers t h a t some unusual TL m a t e r i a l s based on metal s u l f i d e s a r e more s e n s i t i v e f o r high-LET than f o r low-LET r a d i a t i o n , w i t h obvious i m p l i c a t i o n s f o r f a s t neutron dosimetry. Tests have been c a r r i e d o u t w i t h Russian phosphor samples (ZnS;Na,Cu), and i t was found t h a t t h e d o s i m e t r i c p r o p e r t i e s o f such m a t e r i a l s ( s e n s i t i v i t y , s t a b i l i t y , l i g h t response) do n o t make them d e s i r a b l e f o r r o u t i n e dosime t r y f o r t h e time being. Some o t h e r p o t e n t i a l l y i n t e r e s t i n g "new" approaches t o t h e problem o f s o l i d -s t a t e f a s t neutron dosimetry, f o r example on t h e b a s i s o f lyoluminescence i n organics, a r e a l s o discussed. References 1. K. Becker and M. Abd-el Razek, ORNL-TM-4460 (1974), and Nucl.