Physics Chapter 3 Homework

Transcription

1 hysics Chaptr Homwork 1. Which procss is usd in ractors for producing nutrons? am on nuclar raction for nutron production that can b usd in acclrators. (10 pts) 5U + n fission products + n 7Li(p,n), d(t,n). Minium was on of th main rd paint pigmnts availabl to mdival and rnaissanc paintrs. a. How and why dos it show in X-ray radiographs? b. Dos it show in nutron activation? c. What possibilitis dos XRF or IXE offr for analyzing th amount of minium in a painting? (10pts).a. Larg x-ray absorption cross sction on b (lad).b. Dos not show bcaus of low nutron captur cross sction on b isotops.c. Intnsity of charactristic X-ray mission provids information about abundanc of lad

2 hysics Chaptr Homwork You do a IXE analysis and a complmntary nutron activation analysis of th rd coat worn by St. Christophrus in th painting Di virzhn othlfr by Lucas Cranach. a. Th IXE spctrum indicats a mix of vrmillion and lad-whit in th color of th rd coat, what would you s with nutron activation? b. What would a radiograph of th rd coat show? (15pts).a. Rd color is paintd with HgS and b O 4. Using IXE both b and Hg can b idntifid by thir charactristic x-ray transitions (L-transitions). Using nutron activation would only b hlpful for idntifying Hg which transition for th 09 b isotop, it cannot b sn in nutron activation xprimnts..b. Th aras whr th paintr has usd b O 4 can b clarly idntifid bcaus thy show up vry light in th radiograph sinc b absorbs th x-rays. This way th ara is distinguishd from th aras whr HgS has bn usd.

3 hysics Chaptr Homwork 4. You radiat a small sction of Marc Chagall s mrican Windows in th Chicago rt Institut containing balt blu (l O 4 ) with a flux of nutrons for minuts. Th cross sction for nutron captur on is 0.1 barn, th glass sht contains a 0.1mm thick layr of blu and an stimatd ara of 1000 cm. Th nutron activation producs radioactiv with a half liv of 5.7 yars, Calculat how much you produc and dtrmin th ovrall activity 8 days and 80 days aftr th activation procss Th numbr of 15 Totalnumbr of g wb : 4. cm V barn10 s cm cm 10 s cm cm 1cm atoms ;. 1Mol s s of dcay bcaus of th long half - lif of n ( t) (8d ) s g t s (80d) C : 177g particls 177 g g 4. cm (0pts) is drivd from th molcul composition of balt Blu. isotopsproducd in minuts; this corrsponds with thstarting tim ( t) ( t 0) 10 t ln ln T / d 4 s d 18 s cm particls 4 1 cm d

4 hysics Chaptr Homwork 5. nsidr th Rmbrandt s slf-portrait. Th dominating pigmnt is umbr with a 1% contribution of bon black for th undr drawing. utron activation producs radioactiv 56 (T 1/ =.58h) from th umbr and (T 1/ =14.6d) from th bon black. ssuming idntical cross sction for th associatd nutron captur ractions calculat a. th ratio of th production of 56 and ovr th activation priod of 10 h. b. th rlativ activity ( 56 )/( ) aftr a 1d, d, 5d, 8d, and 0d priod following th activation. (0pts) 5.a. 1 1 bon black umbr t t 1 1 ln d ln h 1 n 1 n 1 t t t t d h 1 1 h 6.45d t t 1 1 t t roduction ratio aftr 10h : 10h h 1 1 t t Th amount of radioactiv hosphorus producd in 10 h radiation tim is of th amount of radioactiv Mangans at th nd of th 10h irradiation priod. ftr that both componnts dcay according to thir dcay probabilitis.

5 hysics Chaptr Homwork 5.b. t 0 t 1d 5d 8d d t t d t t Whil initially th Mangans activity from umbr is much highr than th hosphorus activity from th bon black, alrady aftr 1 day th activity lvl is comparabl and aftr days th mangans activity is only about 1 of th hosphorus. Th activity lvl has rvrsd; aftr 5 days th Mangans activity has basically disappard compard to hosphors.

6 hysics Chaptr Homwork 6. You want to dtrmin th isotop ratio of 16 O and 1 8 O as wll as C and C in a sction of th Elgin Marbls, which wr part of th arthnon friz rmovd by th British Lord Elgin in Th isotop analysis will hlp to idntify its provnanc of th matrial. You us an isotop sparator magnt with a magntic fild of 1 Tsla. Calculat th radii of th trajctory of C, 16 O, and 18 O if th radius for C is R=1 m. (10pts) m1 R1 m1 m1 R1 R 1m m R m R( C)=1.08 m, R( 16 O)=1. m, R( 18 O)=1.5 m

7 hysics Chaptr Homwork 7. Using a mass sparator you masur th carbon isotop ratio C/ C to b of Knnwick Man, a mor than 9000 yar old sklton found at th Washington shor of th lumbia Rivr. a. Driv C of th matrial considring that th DB blmnit standard has an isotop ratio of C/ C= b. Basd on this valu, what would you considr was his favorit dit? c. Th worldwid avrag valu for C is -., what is th avrag isotop ratio C/ C? (15pts) 7.a. 7.b. 7.c. C world C C avrag C C C C C C C4 plants and mat C C avrag C C std sampl SMOW C C std C C avrag C 1000 world 1 C C std