Fill in the missing particles or nucs d 5lugy.66halei:
(a) $\text{n} + _{56}^{137}\text{Ba} \to ? + \gamma$
(b) $\text{n} + _{55}^{137}\text{Cs} \to _{56}^{137}\text{Ba} + 2?$
(c) $_{92}^{235}\text{U} + \text{n} \to _{38}^{90}\text{Sr} + ? + 3\text{n}$
(d) $? + \text{d} \to _{79}^{197}\text{Au} + \alpha$
where d stands for deuterium ($_{1}^{2}\text{H}$).

The isotope $_{15}^{32}\text{P}$ is produced by the reaction: $? + \text{n} \to _{15}^{32}\text{P} + \text{p}$. What must be the target nucleus?

When $_{11}^{22}\text{Na}$ is bombarded by deuterons ($_{1}^{2}\text{H}$), an $\alpha$ particle is emitted. What is the resulting nuclide?

Why are neutrons such good projectiles for producing nuclear reactiq)z90 u9ke/ p bi;agpions?

A proton strikes a $_{10}^{20}\text{Ne}$ nucleus, and an $\alpha$ particle is observed to emerge. What is the residual nucleus? Write down the reaction equation.

Are fission fragmento0u8f0 xnip k :/tr5qcnr.*rd s $\beta^+$ or $\beta^-$ emitters? Explain.

  If $_{92}^{235}\text{U}$ released only 1.5 neutrons per fission on the average, would a chain reaction be possible?  ----待选择----yesno 
If so, what would be different?

$_{94}^{238}\text{Pu}$ releases an average of 2.5 neutrons per fission compared to 2.9 for $_{94}^{239}\text{Pu}$. Pure samples of which of these two nuclei do you think would have the smaller critical mass? Explain.

The energy from nuclear fission appears in the form of the7n 1 a)lz8;g mf,fyaa kvji:g6rmal energy - but the thermal energy of wh;: 8 zlaggfk1n76am)vfy a,ijat?

The energy from nuclear fission appears in the form of thermal ene , ,92(yao ;ptnis)u:rp zagfdrgy - but the thermal energy of what9oa t f);ns,gr:u(a p, ziypd2?

Why can't uranium be enricv , rshiy4f(i9hed by chemical means?

How can a neutron, with practically no ki q)pg6gcqtsmx:1 1 adm 7()z qjl2sef8netic energy, excite a nucleus to the ex qps:1 a1ljxt) ge d6q8(mf qm)z7cg2stent shown in (Fig. Below)?

Why would a porous blocker7 q,g3h3c qf of uranium be more likely to explode if kept under water rather than ir3fgchqq 73e ,n air?

A reactor that uses highly enriched uranium can use ordinary water (instead of x lsa-g 5t/t(jheavy water) as a moderator and still have a self-sustaining chain reaction. Explal( g5s xja/t-tin.

Why must the fission process release neutrons if it-q7qy j /)kn(qkz( jaz8w,q ac is to be useful?

Discuss the relative merits and disadvantages, includinirn q8.nosi2q *5n opl:c 8a/gg pollution and safety, of power generation by fossil fuels,.gn8 n5 lc8rqp /qoia*is:no 2 nuclear fission, and nuclear fusion.

What is the reason for the "secondauxlkttm,j3+b te +m229p reu,ry system" in a nuclear reactor, (Fig. Below)? That is, why is the water heatj9lm, teutk2uxtp++bm,3e 2r ed by the fuel in a nuclear reactor not used directly to drive the turbines?

Why are neutrons released in9p vqt7qqi vwiw 22 6z1l41fey a fission reaction?

Why do gamma particles penetrate matter more easils 6hw7rgwzbm 80b y,-cy than beta particles do?

A higher temperature is required/nwlp+ 5djeho 0ata zy, /f5+u for deuterium-deuterium ignition than for deuterium-tritium. Expfzunpjaya+o5 t l/ew +0d/h5 ,lain.

Light energy emitted by the Sun and stars com2f0tbwc85zlh: z3 p,eipb bwl+r * qg)es from the fusion process. What conditions in the i2l wzpbf0)t rqhwe*zl,ig38c5 b+ :pbnterior of stars make this possible?

How do stars, and our Sun, maintain confinement of the plasms wfqw3 y4*hmux v9(/qa for fusion?

What is the basic difference between fissiorve, 91n gz +dpw7v8mjn and fusion?

People who work around metals that emit alpha particles are trained that th5a s/xhrl fk-52-p9gubfe 9wnere is little danger from proximity or even touching the material, but that they must take extreme precautions against ingesting it. Hence, there are -shw2 5fx np-5rkebflu/9 a9gstrong rules against eating and drinking while working, and against machining the metal. Why?

Why is the recommended maximum radiation dose highegf4xek 8t7 t,zr for women beyond the child-bearing age than for younger women?k8t 4etz g7,fx

Radiation is sometimes used to sterilize medical supplies :.;a uo+g s o thskn)6nmes-b:and even food. Explain how it wor:unsm .eaoo6gs tn-+)b:ks ;h ks.

What is the difference betwrr/ +dkwky dra gh17-y 9hx*uq:sj)g3een absorbed dose and effective dose? What are the SI units 9rrq*k +-ydjgrxkwuy:/ sda 71h h3g)for each?

How might radioactive tracers be used to find a leak in a pipeovqpx+pm nzae aidu+ : h12-+5?

Natural aluminum is alljdo 4(26ham b4obtq k, $_{13}^{27}\text{Al}$. If it absorbs a neutron, what does it become? Does it decay by $\beta^-$ or $\beta^+$? What will be the product nucleus?

Determine whether the repu-bzf((tk.0ytqy 0 6 8ghwun*2cq a ewkl52kaction $_{1}^{2}\text{H} + _{1}^{2}\text{H} \to _{2}^{3}\text{He} + \text{n}$ requires a threshold energy.

Is the reaction $\text{n} + _{92}^{238}\text{U} \to _{92}^{239}\text{U} + \gamma$ possible with slow neutrons? Explain.

  Does the reaction $_{3}^{7}\text{Li} + \text{p} \to _{2}^{4}\text{He} + \alpha$ require energy, or does it release energy? How much energy?    MeV

  Calculate the energy released (or energy input required) for tp(3mr4 fzkv rg0 8z:gjhe reaction $_{5}^{10}\text{B} + \text{p} \to _{3}^{7}\text{Li} + \alpha$.    MeV

  (a) Can the reactionym8syr7 3ge)91/9vqz+2vnz faol xmb $_{11}^{23}\text{Na} + \text{d} \to \text{n} + _{12}^{24}\text{Mg}$ occur if the bombarding particles have 10.00 MeV of kinetic energy? (d stands for deuterium, $_{1}^{2}\text{H}$)
(b) If so, how much energy is released?    MeV

  (a) Can the reaction v5zsu 6s5( *w vx yowu4z*wf,l$_{3}^{7}\text{Li} + \text{p} \to _{2}^{4}\text{He} + \alpha$ occur if the incident proton has kinetic energy = 2500 keV?
(b) If so, what is the total kinetic energy of the products?    MeV

  In the reaction $_{8}^{18}\text{O} + \text{p} \to _{9}^{18}\text{F} + \gamma$, the incident $\alpha$ particles have 7.68 MeV of kinetic energy.
(a) Can this reaction occur?
(b) If so, what is the total kinetic energy of the products? The mass of $_{9}^{18}\text{F}$ is 16.999131 u.   MeV

  Calculate the Q-value for thn7z;qa pgd) 1ze "capture" reaction $_{2}^{4}\text{He} + _{4}^{9}\text{Be} \to _{6}^{12}\text{C} + \text{n}$. Q =    MeV

  Calculate the total kinetic energy of the products of t5wvzfc y p 4i2g,lwj4.he reaction $_{6}^{12}\text{C} + \text{d} \to _{7}^{13}\text{N} + \text{p}$ if the incoming deuteron (d) has $KE = 36.3\ \text{MeV}$. $KE_{\text{total}}$ =    MeV

  Radioactive $_{6}^{14}\text{C}$ is produced in the atmosphere when a neutron is absorbed by $_{7}^{14}\text{N}$. Write the reaction and find its Q-value. Q =    MeV

  An example of a "stripping" nucleay9apfndy;.)jtb *df1)jks1 h 1b ms1ar reaction is $\text{d} + _{3}^{7}\text{Li} \to \text{X} + \text{p}$.
(a) What is X, the resulting nucleus?
(b) Why is it called a "stripping" reaction?
(c) What is the Q-value of this reaction? Is the reaction endothermic or exothermic? Q =    MeV

  An example of a "pick-up" nuclear reacti05(gr)g g tl8jygd hn8on is $_{1}^{2}\text{H} + _{6}^{12}\text{C} \to \text{X} + \alpha$.
(a) Why is it called a "pickup" reaction?
(b) What is the resulting nucleus?
(c) What is the Q-value of this reaction? Is the reaction endothermic or exothermic?Q =    MeV

  (a) Complete the following nuclear re2chjkq8ct 2sbnjr-n.a o5 f , uw;)qq-action: $\text{p} + ? \to _{16}^{32}\text{S} + \gamma$.
(b) What is the Q-value? Q =    MeV

  The reaction $_{9}^{19}\text{F} + \text{n} \to _{9}^{20}\text{F} + \gamma$ requires an input of energy equal to 2.453 MeV. What is the mass of $_{9}^{20}\text{F}$?
$m_{^{18}_{9}F}$ =    U

  Calculate the energy release5yya.b w ;h-fkr+m e(sd in the fission reaction $_{92}^{235}\text{U} + \text{n} \to _{56}^{141}\text{Ba} + _{36}^{92}\text{Kr} + 3\text{n}$. Use Appendix B, and assume the initial kinetic energy of the neutron is very small. Q =    MeV

  What is the energy released in the fission reaction of Eq. 31-4? (The masses of 1i2ncn c+ld+rinp4h)q 3xw8 ml2iprdx8wh ) + nn4cm+ cnq1i3$_{56}^{140}\text{Ba}$ and $_{36}^{92}\text{Kr}$ are 140.914411 u and 91.926156 u, respectively.) Q =    MeV

  How many fissions take place per second in a 6rd9f0b -stei200-MW reactor? Assume 200 MeV is released per fission.-69sfdre0i tb P =    $\times 10^{13}\ \text{reactions/s}$

  The energy produced by a fisk,malvr5)u:cmdy1dx9 - q(of sion reactor is about 200 MeV per fission. What fraction of theluym )r 5k9cd qfma(1ov,:dx- rest mass of a $_{92}^{235}\text{U}$ nucleus is this? The ratio is about $\approx 1 : $   

  Consider the fission reaction k+3 2qppuvjqaq:ip pvpj l35r9 3:e v)$_{92}^{235}\text{U} + \text{n} \to _{51}^{133}\text{Sb} + _{41}^{98}\text{Nb} + ?\text{n}$.
(a) How many neutrons are produced in this reaction?   
(b) Calculate the energy release. The atomic masses for Sb and Nb isotopes are 132.915250 u and 97.910328 u, respectively. Q =    MeV

  How much mass of $_{92}^{235}\text{U}$ is required to produce the same amount of energy as burning 1.0 kg of coal (about $3 \times 10^7\ \text{J}$)?    $ \times 10^{-7}\ \text{kg}$

  Suppose that the electric average power consumption, day and night, in a typi8y/1e cdh;ky )nh 9fqccal house is 950 W. Wha f8c cdyeyn1hq);h k/9t initial mass of $_{92}^{235}\text{U}$ would have to undergo fission to supply the electrical needs of such a house for a year? (Assume 200 MeV is released per fission, as well as 100% efficiency.)    $ \times 10^{-4}\ \text{kg}$

  What initial mass of/ve5vvz*x9quc h i.. +drt *iq $_{92}^{235}\text{U}$ is required to operate a 650-MW reactor for 1 yr? Assume 40% efficiency. The initial mass is $\approx $    $\ \text{kg}$

  Assuming a fission ofnxp hwrn*xd5y;q 65l) $_{92}^{235}\text{U}$ into two roughly equal fragments, estimate the electric potential energy just as the fragments separate from each other. Assume that the fragments are spherical (see Eq. 30-1) and compare your calculation to the nuclear fission energy released, about 200 MeV.
PE =    MeV
This is about    % larger than the nuclear fission energy released.

  What is the average kinetic energy of protons at the center of a stkisbqw *g5n7j)i:+ va ar where the temperature iq sn7a+v)g*b w5ki: jis $2 \times 10^7\ \text{K}$?
KE =    $ \times 10^{-16}\ \text{J}$
KE =    eV

  Calculate the energy released zhd)uo5tj :/a hmj915tl,v-u qf c;9 zfkgcn *in the fusion reaction $_{1}^{2}\text{H} + _{1}^{3}\text{H} \to _{2}^{4}\text{He} + \text{n}$ is    MeV.

  Calculate the energy)s/4ncq(si jmuk imd;g5w(:bb d g3p0 released when two deuterium nuclei fuse to form $_{2}^{3}\text{He}$ with the release of a neutron is    MeV.

  Verify the Q-value stated ff/:mg sw8kzb)fn v7 *jor each of the reactions ofEqs. 31-6.
Eqs. 31-6-a Q =    MeV
Eqs. 31-6-b Q =    MeV
Eqs. 31-6-c Q =    MeV

  Calculate the energy release per gram of fuel for the reacti eo5mk2v-i((h vzz4nk8cwj*u- e cxm )ons of Eqs. 31-8a, b, and c. (-eh m5j4k(8 -oviukwzm cce* nz xv)2Compare to the energy release per gram of uranium in fission.
31-8a =    $ \times 10^{23}\ \text{MeV/g}$
31-8b =    $\times 10^{23}\ \text{MeV/g}$
31-8c =    $ \times 10^{24}\ \text{MeV/g}$
Uranium fission =    $ \times 10^{23}\ \text{MeV/g}$

  How much energy is relexn9ihp9/+7wln eui;4.o yn neased when $_{92}^{238}\text{U}$ absorbs a slow neutron ($KE \approx 0$) and becomes $_{92}^{239}\text{U}$? Q =    MeV

  If a typical house requires 950 W of electric power on average, what mix-u a:95dwdmnnimum amount of deuterium fuel would have to be used in a year to supply these electrical needs? Assume the reaction of Eq.31- 8b. aunwx5-:d 9 dm   g

Show that the energies carried off by 7o/ .nm ahf2:zpnyou 7the $_{2}^{4}\text{He}$ nucleus and the neutron for the reaction of Eq. 31-8c are about 3.5 MeV and 14 MeV, respectively. Are these fixed values, independent of the plasma temperature?

  Suppose a fusion reactor ran on "d-d" reactions, E5qjc: adgo-qgt8,g e7qs. 31-8a and b. Estimate how much gagt5 od j- e:c7g8qq,water, for fuel, would be needed per hour to run a 1000-MW reactor, assuming 30% efficiency. $\approx$    $kg/h$

  How much energy (J) is contained in 1.00 kg of water if )etltz:* c)z qits natural deuterium is used in the fusion reaction of Eq. 31-8a? Compare to thet)*leqct ) zz: energy obtained from the burning of 1.0 kg of gasoline, about $5 \times 10^7\ \text{J}$.
   $ \times 10^{9}\ \text{J}$
   times more than gasoline

The energy output of massive sb cr5v1v8e7bn0ap vbi4* y3fvk92rc ctars is believed to be due to the carbon cycle (see text). (a) Show that no carbon is consumed in this cycle and that the net effect is the same as for the proton-proton cycle. (b) What ivv19acpcb42v3fcy78k* r5bb vrn0i e s the total energy release? (c) Determine the energy output for each reaction and decay. (d) Why does the carbon cycle require a higher temperature ($T \approx 2 \times 10^7\ \text{K}$) than the proton-proton cycle ($T \approx 1.5 \times 10^7\ \text{K}$)?

(a) Compare the energy needed for the 2zr46x)uw tof 86t8 n tnn6sxnfirst reaction of the carbon cycle to thatt8nrosxxz4 6 86nwttn)n2f 6u for a deuterium-tritium reaction.
(b) If a deuterium–tritium reaction requires $T \approx 3 \times 10^8\ \text{K}$, estimate the temperature needed for the first carbon-cycle reaction.

  A dose of 4.0 Sv of 9w l8htfs.x;t$\gamma$ rays in a short period would be lethal to about half the people subjected to it. How many grays is this?    $Gy$

  Fifty rads of $\alpha$-particle radiation is equivalent to how many rads of X-rays in terms of biological damage?    rad

  How many rads of slow neutrons will do as much biologican3 j2+,nkro.owgr 6 jbv dx371,p ufzzl damage as 75 rads of fast neutkd,n zg6x z p3o1 rvn7wrbf uj3.+2,jorons?    rad slow neutrons

  How much energy is deposited in thp5b6 au)rpbccy4l, j9e body of a 65-kg adult exposed to a 2.0-Gy dos lr5b 94u6)y ajb,cppce?    $J$

  A $0.025-\mu\text{Ci}$ sample of $_{15}^{32}\text{P}$ is injected into an animal for tracer studies. If a Geiger counter intercepts 25% of the emitted $\beta^-$ particles, what will be the counting rate, assumed 85% efficient?$\approx$    $ \ \text{counts/s}$

  A cancer patient is undergjpip ,r6r4f7 r o-pkv 3z5fp75fu:f fuoing radiation therapy in which protons with an energy of 1.2 MeV are incident on a 0.25-krvup r,7p3r p6o: 4 75fkf -ziupffj5fg tumor.
(a) If the patient receives an effective dose of 1.0 rem, what is the absorbed dose?
(b) How many protons are absorbed by the tumor? Assume $QF = 1$.    $ \times 10^{10}\ \text{p}$

  A 1.0-mCi source of odo167;u1+ hnx1l h c0f+bjbrudad* h$_{15}^{32}\text{P}$ (in $\text{NaHPO}_4$), a $\beta^-$ emitter, is implanted in a tumor where it is to administer 36 Gy. The half-life of $_{15}^{32}\text{P}$ is 14.3 days, and 1 mCi delivers about $10\ \text{mGy/min}$. Approximately how long should the source remain implanted?    day

About 35 eV is required to produce one ion pair in air. Show jce,5hxv ,wlbo08( ubthat this is consistent with the two definitions of thu5 e,oxbwcb0(l, j hv8e roentgen given in the text.

  $_{27}^{57}\text{Co}$ emits 122-keV $\gamma$ rays. If a 70-kg person swallowed $1.85\ \mu\text{Ci}$ of $_{27}^{57}\text{Co}$, what would be the dose rate (Gy/day) averaged over the whole body? Assume that 50% of the $\gamma$ energy is deposited in the body.    $\times 10^{-2}\ \text{Gy/day}$

  What is the mass of a 7g qx8+4 iaksg$1.00-\mu\text{Ci}\ _{6}^{14}\text{C}$ source?    $\times 10^{-10}\ \text{kg}$

  Huge amounts of radioactimswvmeg:2q1 v 1kh;n. ve $_{53}^{131}\text{I}$ were released in the accident at Chernobyl in 1986. Chemically, iodine goes to the human thyroid. (Doctors can use it for diagnosis and treatment of thyroid problems.) In a normal thyroid, $_{53}^{131}\text{I}$ absorption can cause damage to the thyroid.
(a) Write down the reactions for the decay of $_{53}^{131}\text{I}$.
(b) Its half-life is 8.0 d; how long would it take for ingested $_{53}^{131}\text{I}$ to become 10% of the initial value? N $\approx$    $ \ \text{d}$
(c) Absorbing 1 mCi of $_{53}^{131}\text{I}$ can be harmful; what mass of iodine is this?   $ \times 10^{-12}\ \text{kg}$

  Assume a liter of milk typical(h5v)r l zccx;ly has an activity of 2000 pCi due to $_{19}^{40}\text{K}$. If a person drinks two glasses (0.5 L) per day, estimate the total effective dose (in Sv and in rem) received in a year. As a crude model, assume the milk stays in the stomach 12 hr and is then released. Assume also that very roughly 10% of the 1.5 MeV released per decay is absorbed by the body. Compare your result to the normal allowed dose of 100 mrem per year. Make your estimate for
(a) a 50-kg adult, $\approx$    $ \times 10^{-7}\ \text{Sv/year}$ $\approx $    $ \times 10^{-5}\ \text{rem/year}$ $\approx $    $ \times 10^{-4}$ times the allowed dose
(b) a 5-kg baby.   $\times 10^{-4}\ \text{Sv}$    $\times 10^{-4}\ \text{rem}$    $ \times 10^{-4}\ \text{times the allowed dose}$

Radon gas, $_{86}^{222}\text{Rn}$, is considered a serious health hazard (see discussion in text). It decays by $\alpha$ emission.
(a) What is the daughter nucleus?
(b) Is the daughter nucleus stable or radioactive? If the latter, how does it decay, and what is its half-life?
(c) Is the daughter nucleus also a noble gas, or is it chemically reacting?
(d) Suppose 1.0 ng of $_{86}^{222}\text{Rn}$ seeps into a basement. What will be its activity? If the basement is then sealed, what will be the activity 1 month later?

  Calculate the wavelength of photons needed to produce NMR tq wcfe++khe0ycx ,vno98fo ah 6k6* /aransitions in free prot* co+c a+9h8wxfen6k /f,6voqae0 hkyons in a 1.000-T field. In what region of the spectrum does it lie? c =    $m$

  J. Chadwick discoverzp6 k 44oj0pyjed the neutron by bombarding $_{4}^{9}\text{Be}$ with the popular projectile of the day, alpha particles.
(a) If one of the reaction products was the then unknown neutron, what was the other product?
(b) What is the Q-value of this reaction?Q =    MeV

  Fusion temperatures are often gi yo 1r.t)ax/b+d c7gb)qk6n cpven in keV. Determine the conversion factor from kelvins to keV using, as is common in this 7)d 1k/ar ybqg6otbc).+pc x nfield, $KE = kT$ without the factor $\frac{3}{2}$. K =    $ \times 10^{-5}\ \text{keV/K}$

  One means of enrichigw0i8*ez6q3kg /e s ugng uranium is by diffusion of the gas $\text{UF}_6$. Calculate the ratio of the speeds of molecules of this gas containing $_{92}^{235}\text{U}$ and $_{92}^{238}\text{U}$ on which this process depends.    :1

  (a) What mass of $_{92}^{235}\text{U}$ was actually fissioned in the first atomic bomb, whose energy was the equivalent of about 20 kilotons of TNT (1 kiloton of TNT releases $5 \times 10^{12}\ \text{J}$)? $\approx $    $\ \text{kg}$
(b) What was the actual mass transformed to energy?$\approx $    $\ \text{g}$

  In a certain town the average fwfp1- p(ump: yearly background radiation consists of 21 mrad of X-rays and :-up( m1w fpfp$\gamma$ rays plus 3.0 mrad of particles having a QF of 10. How many rem will a person receive per year on the average?dose(rem) =   $ \times 10^{-2}\ \text{rem/yr}$

  Deuterium makes up 0.0115% of naturan.g93h8 :cv 8cd(c wdsi (vwrul)jg0d l hydrogen on average. Make a rough estimate of the total deuterium in the Earth's oceans and estima:3dcur 0)h8(gnvvw9jw ccs(.l 8 didgte the total energy released if all of it were used in fusion reactors.

The total mass of deuterium is about    $ \times 10^{16}\ \text{kg}$
The total energy is about    $\times 10^{30}\ \text{J}$

  A shielded $\gamma$-ray source yields a dose rate of $0.052\ \text{rad/h}$ at a distance of 1.0 m for an average-sized person. If workers are allowed a maximum dose of 5.0 rem in 1 year, how close to the source may they operate, assuming a 40-h work week? Assume that the intensity of radiation falls off as the square of the distance. (It actually falls off more rapidly than $\frac{1}{r^2}$ because of absorption in the air, so your answer will give a better-than-permissible value.)    m

Radon gas, $_{86}^{222}\text{Rn}$, is formed by $\alpha$ decay. (a) Write the decay equation. (b) Ignoring the kinetic energy of the daughter nucleus (it's so massive), estimate the kinetic energy of the $\alpha$ particle produced. (c) Estimate the momentum of the alpha and of the daughter nucleus. (d) Estimate the kinetic energy of the daughter, and show that your approximation in (b) was valid.

  Consider a system of nuclear poweq+5 ovon7 ubv7r plants that produce 3400 MW.
(a) What total mass of $_{92}^{235}\text{U}$ fuel would be required to operate these plants for 1 yr, assuming that 200 MeV is released per fission? $\approx$    $ \ \text{kg}$
(b) Typically 6% of the $_{92}^{235}\text{U}$ nuclei that fission produce $_{38}^{90}\text{Sr}$, a $\beta^-$ emitter with a half-life of 29 yr. What is the total radioactivity of the $_{38}^{90}\text{Sr}$ in curies, produced in 1 yr? (Neglect the fact that some of it decays during the 1-yr period.) $\dfrac{\Delta N}{\Delta t}$    $ \times 10^{6}\ \text{Ci}$

  In the net reaction,, for the proton-proton cb+x 07paudv1 iu;4j hgycle in the Sun, the neutrinos escape from the Sun with energy of about 0.5 MeV. The remaining energy, 26.2 MeV, is available within the Sun. Use this value to calculate the "heat of combustion" per kilogram of hydrogen fuel and compare it to the heh+au0vipdxb4u1jg 7; at of combustion of coal, about $3 \times 10^7\ \text{J/kg}$.    $ \times 10^{-14}\ \text{J/g}$
This is about    $ \times 10^7$times the heat of combustion of coal.

  Energy reaches Earth from the Sun at a rate ocz qrkpp 9r7nsc-475eku n*o*f about $1400\ \text{W/m}^2$. Calculate
(a) the total power output of the Sun,$\approx $    $ \times 10^{26}\ \text{W}$
(b) the number of protons consumed per second in the reaction of Eq.31- 7, assuming that this is the source of all the Sun's energy. $\approx $    $ \times 10^8\ \text{protons/s}$
(c) Assuming that the Sun's mass of $2 \times 10^{30}\ \text{kg}$ was originally all protons and that all could be involved in nuclear reactions in the Sun's core, how long would you expect the Sun to "glow" at its present rate? See previous Problem.$ \approx $    $ \times 10^{11}\ \text{yr}$

  Some stars, in a later st(o9rnx+:* hcv ugps b1age of evolution, may begin to fuse two $_{6}^{12}\text{C}$ nuclei into one $_{12}^{24}\text{Mg}$ nucleus.
(a) How much energy would be released in such a reaction?
(b) What kinetic energy must two carbon nuclei each have when far apart, if they can then approach each other to within 6.0 fm, center-to-center? KE =    $ \times 10^{-13}$ =    MeV
(c) Approximately what temperature would this require?   $ \times 10^{10}\ \text{K}$

  An average adult body containiv,*y*paq3l9iki tep kt2x(t27p- uls about $0.10\ \mu\text{Ci}$ of $_{19}^{40}\text{K}$, which comes from food.
(a) How many decays occur per second?    $\ \text{decays/s}$
(b) The potassium decays produce beta particles with energies of around 1.4 MeV. Calculate the dose per year in sieverts for a 50-kg adult.    $\times 10^{-4}\ \text{Sv/y}$
Is this a significant fraction of the $3.6\ \text{mSv/year}$ background rate?    %

  When the nuclear reactor accident occurred at Chernh )vp(gy 3;w fxm7h4 imxl4)stobyl in 1986, $2.0 \times 10^7\ \text{Ci}$ were released into the atmosphere. Assuming that this radiation was distributed uniformly over the surface of the Earth, what was the activity per square meter? (The actual activity was not uniform; even within Europe wet areas received more radioactivity from rainfall). $\frac{\text{Activity}}{\text{m}^2}$=   $ \times 10^{3}\ \text{decays/s}$

  A star with a large helium abe i7cp/es)z-aundance can burn helium in the reaction $3\ _{2}^{4}\text{He} \to _{6}^{12}\text{C} + \gamma$. What is the Q-value for this reaction? Q =    MeV

  A $1.0-\mu\text{Ci}\ _{55}^{137}\text{Cs}$ source is used for 2.0 hours by a 75-kg student in a physics lab. Radioactive $_{55}^{137}\text{Cs}$ decays by $\beta^-$ decay with a half-life of 30 years. The average energy of the emitted betas is about 190 keV per decay. The $\beta^-$ decay is quickly followed by a $\gamma$ ray with an energy of 660 keV. Assuming the student absorbs all emitted energy, what effective dose (in rem) is received during lab? dose $\approx $    $ \times 10^{-5}\ \text{rem}$

  A large amount of $_{38}^{90}\text{Sr}$ was released during the Chernobyl nuclear reactor accident in 1986. The $_{38}^{90}\text{Sr}$ enters the body through the food chain. How long will it take for 90% of the $_{38}^{90}\text{Sr}$ released during the accident to decay? See Appendix B.$\approx $    y

Three radioactive sources have the same activity, 25 mCi. Source A emits 1.0-Mp *gl*- w/z -as02z4epyhtvwneVpzy*0z/-nw-2h* l etas4 p vgw $\gamma$ rays, source B emits 2.0-MeV $\gamma$ rays, and source C emits 2.0-MeV alphas. What is the relative danger of these sources?

  A 70-kg patient is to be given a medical test involvh-brpy- 3,cn ping the ingestion of $_{43}^{99\text{m}}\text{Tc}$ (Section 31-7) which decays by emitting a 140-keV gamma. The half-life for this decay is 6 hours. Assuming that about half the gamma photons exit the body without interacting with anything, what must be the initial activity of the Tc sample if the whole-body dose cannot exceed 50 mrem? Make the rough approximation that biological elimination of Tc can be ignored. Activity $\simeq $    $\ \text{mCi}$