Fill in the missing particles or .d85iw (. k4a e7hq7g,fhm6qqsfaapinuclei:
(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 5* 5e0rnk; z aqfyt0ny0o3cmq projectiles for producing nuclear reactions?

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 fragments9,bz tl)q5 d(fmj3ds q $\beta^+$ 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 thermal energy - but qqf7n . kt)f4ol/t w*fthe thermfw) *ql4ftnktf./q7 oal energy of what?

The energy from nuclear fission appenr7). pmq2lj ft8 -i4hhx eh8rars in the form of thermal energy - but the the8ep xr q-inmjt )8lr42hhh.7frmal energy of what?

Why can't uranium be enriched by chemical me2ergb.kqt9 t d4 )cvg(ans?

How can a neutron, with practically no kinetic energy, excps25h vc:v/p 8xmd,l cite a nucleus to the extent shown i2p,8c:sd xlvc/mv p5hn (Fig. Below)?

Why would a porous block of uranium bxi 5m6e:vb utu/ wr i/4o8 12dr4uxibme more likely to explode if kept under water rather than in ai xr6u4duboe/i4vi1 b:x2m r8/u mwit5r?

A reactor that uses highly enrii:cpn be( gozhp:2pd.b 8+a)f ched uranium can use ordinary water (instead of heavy water) as a moderator and still have a self-sustain pni)ocz(p :+a ep8 2gdhbb:.fing chain reaction. Explain.

Why must the fission procvx1xqu j31s1d0 nf mfg589y ykess release neutrons if it is to be useful?

Discuss the relative merits and disadvantages, d9/ujy0k 6es5xgf (gbmhkx+rf 0mgs4-)vy1w including pollution and safety, of power generation by fossil fuels, nuclear fission, and nuclear fus by)0-+mgmw j vyh019/sf (gxkgus6ed5xf4rk ion.

What is the reason for the "secondary system" in a nuclear reactor, (Fig(n3pummpr,z lk2x9 w5 .eu v5qiie,r5. Below)? That is, why is the water heated by the53u5qp,i2xru m r.el(np iwkzvm,95e fuel in a nuclear reactor not used directly to drive the turbines?

Why are neutrons released in a f .pwuit27; keuxlc 3i9ission reaction?

Why do gamma particles penetrate maz3evw0med(w tv4: *vitter more easily than beta particles do?

A higher temperature is required for deuterium-deuterium ignwgns8v w.743roehx u 1ition than for deuterium-tritium. Ehv834nrsu eg1wx.ow 7xplain.

Light energy emitted by the /zy(m7:fj9rmwh u)gi Sun and stars comes from the fusion process. What con wmh)/jz:7m9 ygu(ifrditions in the interior of stars make this possible?

How do stars, and our Sun, m-(bh ilob(5 ; ur77jr1bmgyn 5cd 0lyhaintain confinement of the plasma for fusion?

What is the basic diffel,h 55j1qqvh jk.sym8si2- c urence between fission and fusion?

People who work around ml6wqc +wa w0uv0 8opa8etals that emit alpha particles are trained that there is olaucq 8v8+ 0waw0p 6wlittle danger from proximity or even touching the material, but that they must take extreme precautions against ingesting it. Hence, there are strong rules against eating and drinking while working, and against machining the metal. Why?

Why is the recommended maximum radiation dom )siy col2mi;zzw75-se higher for women beyond the child-bearing)iyioz2msc; 5 wl7- zm age than for younger women?

Radiation is sometimes used to sterilize medical suppli w1s4(4 wwhn55ellb lq*- eeebf o6p7ves and even food. Explain how w (- lehfqb561wenb*ow45llsepev 74 it works.

What is the difference bek1x w.lv9oh;u*lc. efw:h 4k wtween absorbed dose and effective dose? What are the SI units f wch9lwf1xvh*:k;l o uk4w ..eor each?

How might radioactive tracers be p +qcai0+/yrgused to find a leak in a pipe?

Natural aluminum is all hj .spr79f yj;xd51zr$_{13}^{27}\text{Al}$. 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 reacs9 83 n pj06czeocaw9gtion $_{1}^{2}\text{H} + _{1}^{2}\text{H} \to _{2}^{3}\text{He} + \text{n}$ 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 releaseq.0j vex49js-hq 8htf3(hiv m d (or energy input required) for the reaction $_{5}^{10}\text{B} + \text{p} \to _{3}^{7}\text{Li} + \alpha$.    MeV

  (a) Can the reaction eo4,3w rm ux9h$_{11}^{23}\text{Na} + \text{d} \to \text{n} + _{12}^{24}\text{Mg}$ 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 reactionh oqr*-+z zz6ol+gn*jxcx3j4 $_{3}^{7}\text{Li} + \text{p} \to _{2}^{4}\text{He} + \alpha$ 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 the "capturl+ d:4qrtb(*kpeoe 7 ee" reaction $_{2}^{4}\text{He} + _{4}^{9}\text{Be} \to _{6}^{12}\text{C} + \text{n}$. Q =    MeV

  Calculate the total kinetic ezbakd fg;. y8s82s3o*w49ws4utns fzx4(raynergy of the products of the 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" nuclear reactiaphwq ikk zyt;2 re33(f)53 ev1 hj(jbon 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"qx)shs/ ui +u)6a msjh*co04 t nuclear reaction 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 nuc yywgj+t/s9 (yk64i y ss ivxkqr4l031lear reaction: $\text{p} + ? \to _{16}^{32}\text{S} + \gamma$.
(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 released in the fission rea5zqq ;m*lgv9;z0b eftction $_{92}^{235}\text{U} + \text{n} \to _{56}^{141}\text{Ba} + _{36}^{92}\text{Kr} + 3\text{n}$. 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 o n/vt 0hj:se7yf :s7yejn0/vth $_{56}^{140}\text{Ba}$ and $_{36}^{92}\text{Kr}$ are 140.914411 u and 91.926156 u, respectively.) Q =    MeV

  How many fissions take place per e7 u;jx/wk 7dtrp7t,zrns7y9 second in a 200-MW reactor? Assume 200 MeV is released per dupr;xt7 k9z7s7yj tw7/ e,nrfission. P =    $\times 10^{13}\ \text{reactions/s}$

  The energy produced by a fissiobg/ndad23gv.h3m li 1n reactor is about 200 MeV per fission. What fraction of bgv31al3in g/m d h.2dthe rest mass of a $_{92}^{235}\text{U}$ nucleus is this? The ratio is about $\approx 1 : $   

  Consider the fission rea,li8hxs,p de)74bx e 9b5xn xbction $_{92}^{235}\text{U} + \text{n} \to _{51}^{133}\text{Sb} + _{41}^{98}\text{Nb} + ?\text{n}$.
(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 avj aa8r-g5x. yebua6 3o.uwkf(ze/m8z erage power consumption, day and night, in a typical hgrybzke-ewumo. 5fz( xa6 3aa/ j 8.8uouse is 950 W. What 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 7z *wa4sly- u4xx z/ll$_{92}^{235}\text{U}$ is required to operate a 650-MW reactor for 1 yr? Assume 40% efficiency. The initial mass is $\approx $    $\ \text{kg}$

  Assuming a fission of wphx/p jce8k8a))woj,y( y3g$_{92}^{235}\text{U}$ 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 hwn 2lq)4r/7y lnx0yeq5 yp k9star where the te/9nxewyn2 75lpy)r0qqy hl4 kmperature is $2 \times 10^7\ \text{K}$?
KE =    $ \times 10^{-16}\ \text{J}$
KE =    eV

  Calculate the energy r 6wa0nj0 cua80 9o4mi5qf mais n3pp;yeleased in the fusion reaction $_{1}^{2}\text{H} + _{1}^{3}\text{H} \to _{2}^{4}\text{He} + \text{n}$ is    MeV.

  Calculate the energy released when two deuterium nuclei fuse zx1x72rokjs wg4nh *6 to form $_{2}^{3}\text{He}$ with the release of a neutron is    MeV.

  Verify the Q-value stated for each of the reactio0 be60kbhr )cw40t mxbns 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 reactions of Eqs. 31-8a, egb o+6t(yrlq4tqe,o524 j hw b, and c. Compare to the energy release per gram of uranium ineb(jl4w og et6r o,+y24t hq5q 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 released w ucxcq0v7va0n zl g31:hen $_{92}^{238}\text{U}$ absorbs a slow neutron ($KE \approx 0$) and becomes $_{92}^{239}\text{U}$? Q =    MeV

  If a typical house requires 950 W of electl;f36 g6/wcn ) oygn zmsi(g9iwxr5/wric power on average, what minimum amount of deuterium fuel would have to be used in a year to sup( goz5; w l/im6cwgxw r)/ysi6n nfg93ply these electrical needs? Assume the reaction of Eq.31- 8b.    g

Show that the energies carried off by t-zfmbkes )w7 zy; b+e4he $_{2}^{4}\text{He}$ 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, Eqs. 31-82ezec+oo9k 9igef, : na and b. Estimate how much water, for fuel, would be needed per hour to run a 1000-MW reace:iekg+o92efo c9z , ntor, assuming 30% efficiency. $\approx$    $kg/h$

  How much energy (J) is contained in 1.00 kg of water if its naturo jsbz ;6z 0qzswhrk+2f744qe+sy-ahal deuterium is used in th+4hjwho fq7;s0k az bs-s 2z4zq+r6eye fusion reaction of Eq. 31-8a? Compare to the 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 stagf001jji gmkbx 0gi 55rs 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 effmji10g5ikj g0b gx 0f5ect is the same as for the proton-proton cycle. (b) What is 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 first reaction of the carbon cycle to thatcudoty,4nd+9g. 15 .s zkctjd for a deuteriumdgsndy tcu,o915 4k dt+zc.j.-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 np8pbdnn/nz9 9m :5y b$\gamma$ 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 dhf 0 -hv;p5newill do as much biological damage as 75 rads of fasvnp; h d0f-h5et neutrons?    rad slow neutrons

  How much energy is deposited in the body of a 65-kg adult exposed to a 2.0-Gy do1w:;qyui/cb c neas4v kfq:+ )s;e cu a: fsqy)v1n+kqc4bwi/:e?    $J$

  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 undergoing radiation therapy in which j gssth7n.*1oy6+ry1 j 0kyvc6 m a)hkprotons with an energy of 1.2 MeV are incidentjs)r+kn6v016 y* a.o g s1ycyj7mhkht on a 0.25-kg 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 .gpz;pcs 0 9ph$_{15}^{32}\text{P}$ (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. b 4uz g6i y9zjzmr8.9tr8utp (Show that this is consistent with the two definitions of t9iy g6tb tzrrj u 8498.zu(pzmhe 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 j ycoz i ;1 5)was2(nuiyv.;gl$1.00-\mu\text{Ci}\ _{6}^{14}\text{C}$ source?    $\times 10^{-10}\ \text{kg}$

  Huge amounts of radioactive 17e*m 4c6b+ pzay.1ules azmb$_{53}^{131}\text{I}$ 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 typically has an acti*j 7b*jqndlb lh 8n/j/vity 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 transitionsppwtwpdj5d+2 vreq/ hv(dx 9c8j+2f:30lt zh in free protons in a 1.000-T field. In what region of the c (rdpd30ht/l5p t2pj+wxdq f9zv ej v82h+:wspectrum does it lie? c =    $m$

  J. Chadwick discovered the neutrolif0v2 *g hq6slpl 7o2n 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 a+ hdy6dsmn f5z4d/t3 tre often given in keV. Determine the conversion factor from kelvins to ken dd/y3md4s5t+h z t6fV using, as is common in this field, $KE = kT$ without the factor $\frac{3}{2}$. K =    $ \times 10^{-5}\ \text{keV/K}$

  One means of enriching 6x9gn a3 d5k n8smrxa(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 yearly background radiation consist n8ik3xh9 bqj gnet0hg(b), p-v,6d xy.o,fjos of 21 mrad of X,nx8 6vhq h,ekbd gpy 0n(o3jj9fgx-b.,toi)-rays and $\gamma$ 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 natural hm.e h+mcfxst6/y3o(m ydrogen on average. Make a rough estimate of the total deuterium inhm63mt/. my+ xs (ocfe the Earth's oceans and estimate 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 power plants that produce 3400 MWbe,(dh ax0 x3ya oid,5.
(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 protw 9w1) gaxzw6exv 9 fl )iab-78/bmghkon-proton cycle 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-k 7b ala1v96mfi9w gex8zbh)/wgw )x of combustion" per kilogram of hydrogen fuel and compare it to the heat 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 S*t40z*ubhzg i db0io+g ju (s9un at a rate of 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 stacqbj k:ja9t )h) r1ff8ge 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 contains pvh,4,u9lji t h9pwj6(:zq hoabout $0.10\ \mu\text{Ci}$ 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 acci0 mv2p3o/. x+k65gjnal yyf otdent occurred at Chernobyl 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 abundance can burn hel/h(2t tnpt0flq (ae2mium 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 havzy/o zaqov u;l-( f5/ee the same activity, 25 mCi. Source A emits 1.0-MeVfz q vo/ea5(y-o;zul/ $\gamma$ 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 tot- 7vp hle;)2vn-szv o be given a medical test involving 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 $    $\ \text{mCi}$