Published by Scientific American LBL-1517 227, No.5, pp.102-110, 1972 r: ,

EXOTIC ATOMS

Clyde E. Wiegand

November 1972

.Prepared for the U.S. Atomic Energy Commission under Contract W -7405 -ENG-48

· For Reference

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This document was prepared as an account of work sponsored by the United States Government. While this document is believed to contain correct information, neither the United States Government nor any agency thereof, nor the Regents of the University of California, nor any of their employees, makes any warranty, express or implied, or assumes any legal responsibility for the accuracy, completene"ss, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by its trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof, or the Regents of the University of California. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof or the Regents of the University of California. " ! SCIENTIFIC an Article from l AMERICAN I

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NOVEMBER, 1972 VOL. 227, NO. 5

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101 LAV _L I \...A f\_l Vll'l~ ------­KAON IN ORBIT An electron in an atom can be briefly replaced with another particle. The resulting new atom yields information on the nature of the nucleus

by Clyde E. Wiegand

he atoms of ordinary matter con­ gen atom, and it will therefore be useful sist of a cloud of negatively to briefly consider the properties of the T charged electrons surrounding a hydrogen atom. The model of the atom positively charged nucleus. The simplest proposed by Niels Bohr in 1913 puts of these atoms is hydrogen, with one the electrons in discrete orbits around electron and a nucleus consisting of one the nucleus. An electron can occupy any proton; the most complex is the latest one of these orbits but not the space in element synthesized by nuclear chem­ between. Each orbit is given a number ists, which has 105 electrons and a nu­ called the principal quantum number cleus made up of 105 protons and 157 and designated n. When a hydrogen neutrons. Most atoms are stable in the atom is in its ground state, that is, its sense that they do not spontaneously state of lowest energy, its electron oc­ change their properties. The exceptions cupies the first Bohr orbit, whose prin­ are the natural and man-made radio­ cipal quantum number is 1. The radius active atoms and what are called exotic of the orbit is 5 X I0-9 centimeter. The atoms. In an exotic atom one of the atom can be excited to higher energy electrons is artificially replaced with states by absorbing a photon, or. quan­ an entirely different negatively charged tum of electromagnetic radiation, from particle. Seven negative particles are an external source. The electron jumps capable of substituting for the electron, to another Bohr orbit, and in I0-8 second and so far five of them have been suc­ the atom spontaneously emits a photon cessfully implanted in ordinary atoms. of its own and the elech·on retums to the Although practically all the mass of an ground state. atom resides in the nucleus, the atom's chemical properties are determined by The orbit to which the electron jumps the number and configuration of the depends on the energy of the photon electrons. Until some 30 years ago the absorbed by the atom: a more energetic only elementary pmticles known were photon will cause the electron to jump the proton, the neutron, the electron and to a higher Bohr orbit (for example, to the positron (a positively charged par­ one where n = 4 or n = 5) than a less ticle with the same mass as the electron). energetic photon will. When the energy In the 1940's studies of cosmic rays re­ of the photon is sufficiently great to re­ vealed another class of charged parti­ move the electron completely, the atom cles: the mesons. Mesons are short-lived is said to be ionized. For hydrogen the particles whose mass ranges between energy of ionization is 13.6 electron the mass of the electron and the mass of volts, corresponding to the energy of a the proton (1,840 times the mass of the photon in the far-ultraviolet region of elech·on). The first man-made mesons the electromagnetic spectrum. A lone were the pions, or pi mesons, created in proton will ultimately attract a free elec­ the 184-inch cyclotron at the University tron or steal one from another atom. The of California at Berkeley in 1948. It new hydrogen atom will emit photons as EXOTIC ATOM IS FORMED when one or was several years-and several cyclo­ the freshly ath·acted electron cascades more electrons of an ordinary atom are ar­ tificially replaced with an entirely different trons-later that negative pions were down to the ground state from the orbits negatively charged particle. In this illustra­ successfully substituted for electrons in with large principal quantum numbers. tion the capture of a kaon (K meson) by a atoms. An exotic atom created by replacing target atom to form an exotic atom is de­ Except for some special modifications the electron with another negatively picted schematically. The kaon is captured all the exotic atoms resemble the hydro- charged particle behaves in much the n ear the lOOth energy level of the kaonic 102 atom (a) . As the kaon drops from one energy level to the next (or­ tion, the shorter the wavelength. Sometimes the kaon jumps more bits in gray), it falls within the electron orbits of the atom (orbits than one orbit at a time. Finally it enters a region near the nuclear in color). The energy that the kaon releases during its fall ejects surface, where it encounters a nucleon (a proton or a neutron). electrons from the outer reaches of the atom (b). These electrons Both the kaon and the nucleon disappear, creating two n ew par· · ~ ' are called Auger electrons. At each succeeding jump toward the ticles: a pion (pi meson) and a sigma hyperon (d). The distances nucleus the amount of energy lost by the kaon increases. Below the of the drawing are exaggerated. If the atom were drawn to scale lowest energy level (ground state) of the electrons the energy is re­ and the nucleus were represented by a dot one millimeter in diam­ leased in the form of X rays (c). The more energetic the X-radia- eter, orbit of the first electron would he almost one meter away.

103 same way. Exotic atoms have two impor­ main electrically neutral one of the perfected in the Lawrence Laboratory tant characteristics. First, for the same atomic electrons is ejected as the meson by the nuclear instmmentation group quantum numbers the radii of the orbits is incorporated into the atom. The mes­ under Frederick Goulding, Richard Pehl are inversely proportional to the mass of on falls from one Bohr orbit to another and William Hansen. When an X ray is the orbital pa1ticle. Second, the energy as it approaches the nucleus that cap­ absorbed in the lattice of germanium levels of the orbits are directly propor­ tured it. Mesons are generally caught in atoms that make up the crystal, it excites J - tional to the mass of the orbital particle. orbits larger than about n = 30, depend­ many electrons in the lattice to higher For example, the pion is 273 times as ing on the specific meson involved. The energy levels. A vacancy in the lattice heavy as an electron; therefore the di­ replacement process takes about 10-11 left by an excited electron can be re­ ameter of the pionic atom is 1/ 273rd second; the capture time must of course garded as a hole. The electron-hole pairs the diameter of the hydrogen atom, and be sho1ter than the lifetime of the mes­ act as carriers of electric charge. In our the energy required to make the pion on. As the meson cascades through the experiments the X rays deposited their jump from one orbit to another is 273 orbits, it radiates photons in the form of energy within the crystal in the form of times the energy required for an elec­ X rays. It is by measuring the X-ray electron-hole pairs, and the number of tron to make the same jumps in the photons that we study exotic atoms. charges was proportional to the energy hydrogen atom. In our experiments the mesons were of the X rays. Electrical pulses produced In order to make exotic atoms with produced in the Bevatron, the 6.2- by the charges were amplified and con­ negative mesons the mesons are created billion-electi'on-volt accelerator at the verted to digital numbers. The numbers, in an accelerator and directed at a suit­ Lawrence Berkeley Laboratory. X-ray whose magnitudes were proportional to able target. The mesons are slowed detectors, the heart of the apparatus, the energy of the X rays, were recorded down and brought to rest by their inter­ were placed near the target. One of the on magnetic tape. A computer sorted action with the atomic electrons that are most successful detectors was a single the energies and tabulated them into the bound to the target nuclei. Ultimately cylindrical crystal of ultrapure germa­ spectmm of the exotic atom [see illus­ the strong attraction of a positive nucle­ nium two centimeters in diameter and tration on page 108]. The excellent reso­ us draws the negatively charged meson four millimeters thick. The detectors and lution of these spectrometers allowed a toward it. In order for the atom to re- the associated electronic apparatus were wealth of information to be recorded from the exotic atoms produced by the Bevatron.

Two kinds of exotic atom have been known for almost 20 years. One is the pionic atom; the other is the muonic atom, made with muons, or mu mesons. t' X rays from pionic atoms were first stud- ied by Morton Camac, A. D. McGuire, Joseph B. Platt and Harry J. Schulte at the University of Rochester in 1952. A year later ValL. Fitch and James Rain- water conducted experiments on muonic · atoms at Columbia University. In more recent years interest in such atoms has been rekindled. The behavior of muonic atoms has provided much information about the stmcture of the nucleus, particularly about the distribution of protons within nuclei. Muons are particularly valuable for probing the interior regions of nu­ clei because they interact only with the electric charge of the protons and do not n=4 "feel" the strong nuclear force that binds the nucleons (neutrons and protons) to­ gether. Since the size of the orbits is in­ versely proportional to the mass of the n = 5 orbiting particle, some of the muonic orbits of low principal quantum number are so small that they actually lie within the nucleus [see "Mesonic Atoms," by n=6 Sergio DeBenedetti; SciENTIFIC AMER­ ICAN, October, 1956]. BOHR MODEL of the atom assigns the electrons to discrete orbits around the nucleus. The most abundant of the particles Each orbit is given a principal quantum number (n). The ground state of the atom is that can make exotic atoms are still the n = 1; higher levels are n = 2, n = 3 and so on. The radius of each orbit is proportional .,) 2 ) to n • Where n is large, the electron can easily be stripped from the atom. Radius of the pions. Like muons and electrons, pions n =I orbit of hydrogen is 5 X 10-9 centimeter. The Bohr model also applies to an exotic feel the electromagnetic force of the hydrogen·like atom except that all the Fadii are smaller in proportion to the mass of the nucleus, but in addition they are agents orbital meson. For kaonic hydrogen the radius of the n = 1 orbit is 5 X 10-12 centimeter. of the nuclear force. This force between l04 BEVATRON at the Lawrence Berkeley Laboratory of the Univer­ huge circular magnet. The magnet is 120 feet in diameter and sity of California is one accelerator that has produced meson s for weighs 10,000 tons; the men standing on top of the machine indi· the study of exotic atoms. It is capable of accelerating particles up cate its scale. Particles circle the chamber four million times in 1.8 to an energy of 6.2 billion electron volts (Be V). At lower right is a seconds, close to speed of light. In that time they travel some linear accelerator that injects protons into a chamber within the 300,000 miles, farther than the distance from the earth to the moon. nucleons, and between pions and nu­ emulsions. Although the emulsion exper­ kaons injected into targets of the light cleons, acts only over a very short range: iments did not reveal X rays, they did elements lithium, betyllium, boron and some 10·13 centimeter. It manifests itself show that electrons and the reaction carbon. in violent interactions that can cause products of kaons were ejected from the particles to change from one species to silver atoms of the emulsion in a manner Bearns of kaons are much more expen- another. Some 1,000 times stronger than consistent with the formation of kaonic sive to make than beams of pions or the electromagnetic force, it is often atoms. To the best of my knowledge the muons. Pion and muon beams can be called simply the "strong force." In this first attempt to observe the X rays from produced with cyclotrons of moderate terminology many particles are said to kaonic atoms was made by Joseph Mur­ energy; for all practical purposes nega­ react "strongly." ray and Nahmin Horwitz at the Berkeley tive kaons can be made only by ma­ The precise energy levels of pionic Bevatron in 1958. They saw one line in chines that can accelerate particles to atoms should be predictable from knowl­ the X-ray spectrum of carbon, but be­ energies of more than five billion elec­ edge of the pion-nucleon interactions. cause the resolution of the detector was tron volts. Up to now, however, some of the calcu­ inadequate the experiment was discon­ Negative kaons interact violently with lated levels have not agreed very well tinued. (Ge~manium semiconductor de­ both neutrons and protons. The investi­ with the levels observed in experiments. tectors had not yet been invented.) The gation of kaonic atoms therefore yields The study of pionic X rays has nonethe­ first report on " K - -mesonic" X rays was information on the nature of the surfaces less yielded the most accurate value for published in 1965 by G. R. Burleson, of nuclei. Are the surfaces smooth or the mass of the pion. David Cohen, Richard C. Lamb, Daniel granular? Do they show equal numbers My own primary interest has been in N. Michael, R. A. Schluter and Thomas of neutrons and protons? Or do they exotic atoms formed with the particles 0. White, who were working at the Ar­ have more neutrons than protons, as was known as kaons (K mesons) and sigma gonne National Laboratory. They used proposed by Montgomery Johnson and hyperons. The investigation of these as a target helium: one of the most diffi­ Edward Teller in 1953 on the basis of atoms and the atoms formed with anti­ cult but important elements to try. Again theoretical considerations [see "The Tex­ protons (negatively charged protons) has the results were not entirely convincing, ture of the Nuclear Surface," by Chris begun only quite recently. After pions mostly because the resolving power of D. Zafiratos; SciENTIFIC AMERICAN, and muons had been put in orbit around the detector was inadequate and the October]? We already know the distri­ nuclei, negative kaons were logically the level of background "noise" in the data bution of protons from earlier investiga­ next particles to be tried. Some evidence was high. In 1966 Dick A. Mack and tions that showed how electrons are scat­ that kaonic atoms could be formed was I, working with silicon semiconductor tered by nuclei and how muonic atoms provided by the tracks of kaons stopped detectors at the Bevatron, succeeded behave when the muons orbit within the in specially prepared photographic in measuring several X-ray lines from nucleus. Electrons and muons do not,

lOS however, sense the presence of neutrons. from the outer regions· of the atom. thus could not make the jump from n = Observations of low-energy kaons in These electrons are called Auger elec­ 4 ton = 3. For a transition starting from their encounters with neutrons and pro­ trons. At each succeeding jump toward an orbit of a given principal quantum tons in bubble chambers suggested that the nucleus the amount of energy lost b)'i number the intensity had been predicted the kaons could be used as probes be­ the kaon increases, until X rays become to drop quite suddenly as heavier nuclei cause their behavior at the nuclear sur­ the dominant means of shedding the (nuclei with more charge) were used as face could be predicted. The number of energy. Each jump of the meson be­ the target. Increasing the charge of the reactions involving kaons at certain dis­ tween certain orbits results in the emis­ nucleus shrinks the kaonic orbits and tances from the nuclei should in some sion of an X-ray quantum of an energy brings the kaons closer to the nucleus; in way be proportional to the number of and wavelength belonging to that tran­ addition the radius of the nucleus itself \- - nucleons encountered at those distances. sition. Finally the kaon enters a region increases slightly. On the assumption Whenever a kaon encounters a nucleon, near the nuclear surface, where it has a that protons and neutrons are equally both particles disappear and two new chance to encounter a nucleon in the distributed on the nuclear surface, the­ particles appear: a pion and either a "rarefied nuclear atmosphere" [see illus­ ory predicted that the termination of the sigma hyperon or a lambda hyperon. As tration on pages 102 and 103] . · series of X-ray lines would be a function in chemical reactions we must be careful We interpret the disappearance of the of the number of protons. Our kaonic X­ to balance the equation: the electric X-ray lines in the spectrum of our mea­ ray experiments of 1968 indicated, how­ charge and the pertinent quantum char­ surements as a signal that the kaons have ever, that kaons encountered nucleons acteristics of the particles must ·be equal reacted with nucleons on the nuclear at distances fmther from the nuclear sur­ on both sides of the equation. surface. For example, in certain ele­ face than had been anticipated. We the­ Let us imagine the sequence of events ments the intensity of the X-ray lines for orized tl1at the kaons reacted with a low­ from the moment a -negative kaon is cap­ b·ansitions between lower orbits (such as density halo of neutrons above the main tured by an atom. The kaon has replaced from n = 4 to n = 3) is less than the in­ nuclear surface. one of the inner electrons of the atom tensity for transitions between higher and is established in an orbit of about orbits (such as· n = 5 ton= 4). This de­ There is no complete agreement n = 30. The kaon is strongly attracted to crease in intensity means that some of among theoreticians concerning the the positively charged nucleus. It jumps the kaons were absorbed from the n = 4 interpretation of the experiments. At down to a lower orbit, and at this stage orbit. If the intensity had dropped by the European Organization for Nuclear of the process the energy liberated is half, we could say that half of the kaons Research (CERN) in Geneva, T. E. 0. most likely to eject additional electrons were absorbed from the fourth orbit and Ericson has devoted considerable effort to the understanding of pionic and ka­ onic atoms. He believes the observed de­ LIQUID NITROGEN RESERVOIR creases in X-ray intensity can be calcu­ lated on the assumption that protons and neutrons are present at the nuclear sur­ face in equal numbe1·s. On the other g hand, the notion that nuclear surfaces are dominated by neutrons has been put CERENKOV forward by several physicists since John­ COUNTER son and Teller made their original pre­ diction. The theoretical calculations are based on the concept that the nucleons will arrange themselves in a configura­ tion that allows the total energy of the system to be at a minimum. An analogy is the fact that a free drop of liquid takes the shape of a sphere if it is not dis­ tmbed by outside forces. When all the known properties of nucleons are ap­ plied to the picture of nuclear matter, the configuration that results is one in which the neutrons have a slightly larger radius of distribution than the protons. There are further complications in the simplified conclusion that the observed kaonic X-ray spectra show that nuclei /- have a skin of neutrons. The negatively LIQUID NITROGEN ELECTRONIC charged kaons and positively charged RESERVOIR AMPLIFIER protons attract each other with par­ ticular sb·ength under special circum­ X RAYS FROM KAONIC ATOMS were detected by the apparatus depicted in this draw· stances. This effect might cause the ing. The targets were mounted on a wheel and could be selected at will. Two (sometimes kaons to react more strongly with pro­ three) germanium or silicon detectors were placed near the target. The detectors were cooled by liquid nitrogen to suppress background "noise" in the data. Beam counters tons bound in nuclei than had been an­ ticipated. (S1, S2 and S3 ) signaled the arrival of the kaons at the target. Response from detectors was amplified electronically and recorded on a chart as the X-ray spectra shown on page 108. The early demise of kaons might then

106 be attributed to a voracious appetite of ANGULAR MOMENTUM QUANTUM NUMBERS some protons rather than an overpopula­ 0 2 3 4 5 6 7 8 9 ... tion of neutrons. Another factor that comes into play is that the affinity of kaons for nucleons is so strong the orbits 00 of the kaons are pulled in closer to the 10 -0.14 nucleus than they would be for par­ ticles that do not react so strongly. These effects and others would modify the 9 -0.17 simple picture suggested by the exotic hydrogen atom. Quantitative estimates of these effects 8 -0.21 are controversial. It is apparent that ad­ ditional data and calculations will be needed to resolve the details of the struc­ ture of the surfaces of nuclei and the dis­ 7 -0.28 tribution of neutrons within the nuclei. ~ Up to the present time most of the ex­ - ~ 0 l­ > periments on kaonic atoms have been iD z a: 6 - 0.38 done at Berkeley and at CERN, where 0 ~ an active group is directed by G. Backen­ J: t> () w ...J stoss. Other groups at Argonne and at <( w UJ ---7 the Brookhaven National Laboratory a: ~ have recently joined in the investiga­ 0 z tions. In spite of the complications phys­ ~5 -0.54 ~ 0 icists working on exotic atoms are confi­ a: a: UJ a dent that their studies will lead to a tO >­ :E J: clearer picture of nuclei. ::J -y 11. z 0 ~4 --,- -0.85 r!! x-ray spectra of exotic atoms made 1- z 1 iii with antiprotons were fhst observed <( a: by the CERN group in 1970. The anti­ ::J I 0 a I 11. proton was discovered with the Berkeley ...J I 0 <( Bevatron, but the · machine does not a. ~ () w make a beam of antiprotons with suf­ > z 3 ~ - 1.51 ~ ficient intensity to produce antiprotonic a: a. >- X-ray spectra. Antiprotonic atoms emit w~ X-ray spectra that are similar in appear­ z ance to kaonic X-ray spectra, but there is w one significant difference that has re­ c~ntly been observed. If we could see all the lines at high resolution, we would al­ -3.40 most certainly find that each line is a doublet, that is, it is made up of two separate lines. The lines are split because antiprotons and protons possess spin and magnetic moment. They behave as if they were spinning magnets. Some have their north pole "up" with respect to their orbital motion around a nucleus L------=------=--~ -13.6 and some have it "down." In antipro­ ENERGY LEVELS and angular-momentum quantum number s of a hydrogen-like atom are tonic atoms the energy levels of the shown. The principal quantum number (n) for each orbit is indicated in the vertical scale various orbits of the antiproton around to the left. The vertical scale to the right shows the energy level of each orbit in hydrogen; • the nucleus are slightly different de­ for example, it would require an energy of 13.6 electron volts to take an electron in the pending on whether the spin is "up" or ground state (n = 1) completely out of the hydrogen atom. Exotic atoms can be considered "down." The X-ray lines of the spinning hydrogen-like systems. The arrows show the main transitions a meson makes as it falls particles are thereby split into two com­ toward the nucleus after being captured. Some 10 percent of the particles skip an orbit as ponents, and the amount of splitting can they fall, say from n = 6 to n = 4 without pausing at n = 5. The energy in electron volts be calculated. of each orbit of an exotic atom is given by the relation -13.6(Z2 j n2) X mass of the The magnetic moments of protons orbital particle divided by the mass of the electron. Z is the number of protons in the nucleus and n is the principal quantum number. For example, mass of a kaon divided by and antiprotons are believed to be ex­ mass of the electron is 966. The n = 4 orbit of a kaon around a chlorine nucleus has an actly equal except for their algebraic energy of 237,000 electron volts. For the n = 5 orbit the energy is 152,000 electron volts. sign. This assumption is based on some The difference between these two energies is 85,000 electron volts. There is a tall peak in of the most sacred symmetry principles the X-ray spectrum of chlorine at this energy, corresponding to the transition from the in physics. The belief is that if all the n = 5 orbit to the n = 4 orbit (see the carbon tetrachloride spectrum on the next page).

107 charges were interchanged (negative for ments are accurate enough to afford an to appear along with the X-ray lines positive), all the position coordinates ultimate test of the theorem by this from kaons. were interchanged ( -x for +x and so on) method. Meanwhile antiprotonic atoms In a kaonic X-ray spectrum of potassi­ and time ran backward, the results of all are expected to take their place along­ um obtained in the Berkeley experime_nts experiments in the "negative" world side pionic and kaonic atoms as probes of 1968 there was a line at 136,000 elec­ would be the same as those in the "posi­ of the nucleus. tron volts that corresponded to the tran­ tive" one. Physicists like to test the theo­ As I have mentioned, kaons react with sition energy of a sigma-minus hyperon rem of invariance at every opportunity. nucleons to form pions and hyperons. when it jumps from the n = 6 orbit to A split X-ray line in the spectrum of Many of the hyperons are ejected from the n = 5 orbit. Some two years later the antiprotonic uranium was observed last the nuclei in which they are formed. CERN group confirmed the formation of summer by a group of physicists at Their kinetic energy is sufficiently low sigma-minus hyperonic atoms by identi­ Brookhaven. They found that the mag­ for them to have a high probability of fying several spectral lines of the tran­ netic moment of antiprotons was op­ staying in the target in which they origi­ sitions of sigma-minus hyperons in chlo­ posite in sign to the magnetic moment nate. They are slowed down, come to rine and zinc. The X-ray lines of sigma­ of the protons and agreed with the pre­ rest and are captured in the same way hyperonic atoms have appeared in the dictions of symmetry. It will probably be that kaons are captured by nuclei. Thus kaonic spectra of elements as light as some time, however, before measure- X-ray lines from hyperons were expected lithium and in the medium-heavy ele-

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SPECTRA OF X·RADIATION from kaonic atoms are shown for K8 ~ 7 means that the transition was made by a kaon jumping from targets of carbon tetrachloride ( top ) and sulfur (bottom). The en· its n = 8 orbit to its n = 7 orbit. In the carbon tetrachloride target ergy of the spectrum in each case increases toward the right, and most of the transitions occurred in chlorine atoms. Transitions in the intensity of the X-ray lines increases toward the top. K stands carbon atoms are labeled [C), for example K[C)4~3. The stars ,..- for a transition made by a kaon, ~ for a transition made by a sigma stand above the spectral lines that were created not by kaonic hyperon and 1r for a transition made by a pion. The numbers indi­ X rays but by gamma rays that were emitted by excited phosphorus cate which orbits were involved in the transition. 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Satisfaction guaranteed- 30 day a remote location job hunting. money back return privileges. • How & when to exaggerate In an interview · In addition to hundreds of the latest job • How to Identify lirmo behind blind ads • How to lind out the comment• made by hunting ideas, this revolutionary book contains ••••••••••• your references m·er 5,000 sources for interviews, and dozens of • How to maintain absolute secrecy successful letter and resume examples. • How to negotiate an employment contract Written to provide all the practical tech­ JOB CHANGE WORTH $100,000+ • How to overcome senior age barriers niques and aids known today, it is the I st book Note: You can probably increase your • How to get Interviews ahead of more published by the staff of a Professional Job career eamings by $100,000, through executing qualified candidates Hunting Counseling firm . As specialists, our an intelligent and effecth·e job campaign. In • How to develop & execute a planned knowledge is unsurpassed, and several members campaign-that Ia totally diHerent from fact, once you ha1 ·e knowledge of this book's your competitors of our staff are among the most imaginative and ideas, the only factor that will restrict your • How to handle 1-industry experience keenly analytical individuals in the job chang­ grow1h, will be the extent to which you decide • How to negotiate a maximum salary ing field. to execute them. • How, when & where to successfully run This book has been purchased by Congress­ (i.e., A man of30 who ad•·ances from position wanted ads men, Senators, and Corporate Presidents. More a $12,000 to $16,000 job, will gen­ • How to control virtually any Interview -important, however, tens of thousands of job erally maintain that differential for • How to handle a 1-company background hunters, from students to senior executives, the majority of his career. In thirty • How & when to walk out of an Interview have been personally using it to maximum ad­ years this means $120,000 additional • How & when to use 3rd party techniques vantage in advancing to better jobs. income. Of course, for th ose at higher • How to handle youth and lack ol salary le1·els, the career impact of a job experience barriers change frequently exceeds $250,000.) Any ol the hundredo of advanced Ideal can be mastered by using the recommended tech· WHAT REVIEWERS SAY ABOUT niques, because of the easy-to-use professional program format of the book. Every page has a WHAT INDIVIDUALS SAY subject Index for quick reference, and there are AMERICA'S BEST SELLING dozens of extraordinary letter & resume samples Of greatest significance perhaps are the which are proven Interview producers. JOB HUNTING BOOK opinions of those who have purchased and used this book (the following authentic and This book has been recommended by over unsolicited comments represent only a fraction 100 leading media, including Business Week, of the similar correspondence on file In our who devoted a 650 word article to just a few offices). of its unique ideas. It has received universal • "Your book is priceless! I got a number of praise in all reviews-and ll'as also stirred offers." G. L., New Jersey widespread controversy as many believe it • "Very worthwhile and full of constructive will gradually revolutionize job hunting material." S. B., Massachusetts • "Outstanding! By far the best work ever methods in the U.S. in this field." G . G., New York • "A breakthrough manual which gives in­ • "Well written and concise. Extremely di,·iduals a complete sotace of professional effective for one who is job hunting knowledge and all the materials needed for the first time in a while. I got 42 to execute an effective campaign." interviews." K. B., Illinois Personnel Magazine • "Your ideas are worth their weight in • uA professional program for getting a gold to anyone after a higher salary." Performance Dynamics Inc., Publishing Div. better job in the $10,000 to $60,000 D. A., Missouri range in all fields." • "Thank God for your book. I was un­ 17 Grove Ave., Verona, New Jersey 07044 • "Includes comolete lists of contacts I a employed for 7 months, but with your All orders shipped within 24 hours. Sat­ make and incredibly eOect i• ·e letters and plan have landed my best job. My Isfaction guaranteed--30 day money back resumes. Excellent new book. A good in- sincerest thanks." J. W., Iowa return privilege. '·estment! Nation's Business • "This book was fantastic. Have read it 3 Please Ship: • "The professional secrets of job hunting- times and am very optimistic." G . B., Fla. all of them are in The Professional Job • "A great personal aid. Paid for itself 300 0 The 1973 edition of The Professional Job Hunting Sysrem." Purchasing Week times over." L.A., Indiana Hunting System @$9.95 • "Just the cold hard facts on how to insure • "Most useful book I have ever read." 0 The Performance Dynamics Job Hunter's your getting that job you want. All the R. K., California Contact List @$4.95 secrets are detailed! It's amazingly read­ • "An absolute classic on the modern art Note: offer valid until 1131173 able and highly recommended!" of job hunting." R. G., Wisconsin Memphis Press-Scimitar • "In 4 weeks, I changed jobs and increased 0 Enclosed is my check or Money Order • "Honest-to-God, The Professional Job my earnings 33%. I wish I had it I 0 0 Chg American Exp. Huming System tells you how to get a years ago." E. K., Arizona 0 Chg Bank Amer. 0 Chg Diner's Club job and contains some of the best "Puts you in such a successful frame of addce I've erer read." mind, that it alone is worth the price." Training in Bus. & Ind. C. C., Pennsylvania Acct.# Exp. Date • "Prepares readers to go after a future • "Really terrific-have been in Personnel job like an expert." New Orleans Star 20 years, but never saw anything like Name • "The 1st master reference on job hunting­ this." R. H., Texas makes available for the I st time, many • "A great book! Tells you precisely what nzethods and techniques." to do, and how-to-do-it." S. H ., Calif. Street • Rockford, Ill. Register Star • "Perhaps the most readable and • "The Je chniques are capable of catapulting actionable book I have ever read." City State Zip almost any a\·erage person into a position F. W., New Mexico offering much greater financial rewards." Please Note: Books are shipped separately. • "An invaluable source of potential For faster delivery add tor each book: spec. The National Public Acc't. financial gain." W. F., Tennessee L ~~.;.9~ ~,.:i~~o.;. ____ - ·- _ .J The professional Job Hunting System has been nationally advertised in the N.Y. Times. The Army Times. The Chicago Tribune, Signature, Time:'·Holiday Inn, The Wall Street Journal, The Los Angeles Times, Penthou.,e. The College Placement Journal, Nation's Business, Chemist, New York, True and other leading media. An attractive and extremely useful gift, it prm·ides fascinating information for anyone in business who may e1•er seek to advance. © 1972 Performance Dynamics, Inc., 17 Grove Ave., Verona, N.J. 07044

109 ments. At the present time no lines have the sigma-minus and the omega-minus is been found in the spectra of the heavy 40 percent heavier. The-two particles are elements. so scarce and so difficult :to produce, The intensity of the lines for sigma however, that the tracks of only some hyperons is about 2 percent of the in­ 10,000 xi-minus particles and of a mere tensity of the principal lines for kaons. 25 omega-minus pa1ticles have been Several factors contribute to the low identified in bubble chambers at the intensity. First, only some 8 percent largest accelerators. Perhaps the more of the kaons react to make negatively powerful machine now in operation at charged sigma hyperons. Second, after the National Accelerator Laboratory in the hyperons are created, many of them Batavia, Ill., and the one under con­ interact with the nuclei in which they sttuction at CERN will p1'oduce suffi­ are formed. Third, some of tqe hyperons cient numbers of xi-minus and omega­ decay into other particles while they are minus particles to make it possible to being slowed down or while they are in identify atoms of the last two candidates higher energy orbits. on the present pa1ticle list. The Celestron 5 . .. a complete astronomical telescope weio;Jhing only 12 pounds that fits into an Like many other subatomic particles, In con'clusion I should like to relate 8xl2xl8" carry1ng case. Its Schmidt-Cassegrain optics give you sharper images over a wider f lat field than hyperons have spin and possess a mag­ how the study of one subject can lead to any other telescope currently avai lable. At $595, a netic moment. They are found in three another subject in this fascinating re­ best buy for the telescope novice who wants the finest terrestrial telescope for nature studies or tele­ forms: the sigma-plus (positively search that involves both high-energy photography. charged), the sigma-zero {uncharged) physics and nuclear physics. Let us re­ The larger Celestron 8 shown above is the serious ..,mateur astronomer's dream instrument. light ~ra s p and the sigma-minus {negatively turn briefly to pionic and muonic atoms . is 500 times that of the unaided eye and magn •fica• tion range is 50 to SOOX , resolution '12 sec., weight charged), and in the antiparticles of In addition to X-ray lines the spectra of 23#, price $895. these forms. The magnetic moment of these atoms showed gamma-ray lines The Celestron 14 ••• a permanent observatory telescope for the college installation or the most ad­ the sigma-plus has been crudely mea­ that had come from excited states of vanced amateur astronomer that is so compact that an individual can, in five minutes, demount this 85# sured by observing how the particle pre­ nuclei formed in the targets in which instrument and load it" into his ClH for a remote star cesses in powerful magnetic fields. The the mesons had stopped. The mesons party outing , . $3600. - financing . orientation of the sigma-plus particles in carried energy to the interior of the nu­ "Celestron Techniques" our periodic.,! on ostrophofogrophy and ob­ the field was determined by observing clei and raised the protons and neutrons serving $2 for 4 issues. Send for free pomphlet on whet to e~ped !td:s~~d~';k,~h~~ os~:~;~ th~~~h ~~~:c~e T~~~~~~: .ting of test the direction taken by the particles into to excited levels, in somewhat the same which the hyperons decay. way that the electrons of atoms 'are 2430 Ams Ier Box 3578 &,Celestron Pacific Torrance, Calif. 90505 ' · raised to excited states. When the nuclei when sigma-minus hyperons decay, fall back to their ground level, radiation they do not emit particles that sig­ is emitted in the form of gamma rays. Plant a THINK TANK anywhere nal their orientation. Hence their mag­ Now, when we were getting our kaonic and watch the minds grow! netic moment cannot be measured by X-ray spectra, we were asked many home-office-school-park-club-churches-laboratory the method that works with sigma-plus times: "Why don't you see nuclear gam­ hyperons. The measurement of the sig­ ma rays along with the kaonic X rays?" ma-minus magnetic moment would be In some of the spectra there were a few impmtant to particle physics. The study low-intensity lines that we had not been of sigma-minus hyperonic atoms offers able to attribute to exotic atoms. We this possibility if we can observe the finally did identify these lines as nuclear doublet structure of the X-ray lines. The gamma rays. Unique instructional games designed by uni­ amount by which the lines are split is versity professors to make learning fun proportional to the fourth power of the The relevance of gamma rays induced through brain-to -brain action. Beginning games atomic number {the number of protons). by kaons has not yet been assessed, can be mastered by young children--final games will challenge intelligent adults. These are Therefore the heavier the element, the but a significant aspect of kaonic reac­ the famous GAMES FOR THINKERS from easier it should be to resolve the doublet tions is the following. When a kaon en­ WFF 'N PROOF Publis hers. WFF'N PROOF (logic) $8 .75 pairs of X-ray lines. The splitting will counters a nucleus, it sometimes trans­ QUERIES ' N THEORIES (science) 8.75 nonetheless be difficult to observe, par­ forms a neutron into a lambda hyperon, EQUATIONS (mathematics) 5 .50 ticularly if few sigma-minus atoms are forming what is called a hypemucleus. ON-SETS (set theory) 5 .50 PROPAGANDA (social studies) 6 .50 made in heavy elements. Even if the For example, the hypernucleus lambda­ ON-WORDS (word structures) 5 .50 lines cannot be completely resolved, helium 4 consists of two protons, a neu­ CONFIGURATIONS (geometry) 5 .50 TRI-NIM (problem solving) 4 .50 it may be possible to set a meaningful tron and a lambda hyperon. Hypernuclei REAL NUMBERS (arithmetic) 2.25 upper limit on the magnetic moment of are expected to emit gamma rays that WFF (beginner's logic) 1.75 the sigma-minus hyperon. Sigma-hyper­ will be of considerable interest because QWIK-SANE (puzzle) 1.75 TAC-TICKLE (pure strategy) 1.25 onic atoms may also add to the informa­ the energy of the radiation will yield in­ Teacher's Manual 1.25 tion gained from other exotic ~ toms in formation on the force between the RODIN'S THINKERS BOOKENDS 11.00 Complete 12-kit THINK TANK & the mapping of nuclear surfaces. lambda hyperon and nucleons. That Teachers Manual What is the possibility of making force is a manifestation of the strong with bookends (Save 10.25) 59.50 other exotic atoms? In the table of sub­ force, the nature of which is one of the without bookends (Save 9 .25) 49.50 atomic particles there are two more can­ fundamental questions facing physics. It Order from: WFF 'N PROOF, 1111-DJ Maple Aveuue, Turtle Creek, Po. 15145 didates: the xi-minus and the omega­ is possible that these gamma rays will be •postage included in above prices fully guaranteed. Dealer inquiries invited. minus. Their lifetime is roughly the same made accessible by a refinement of the as the lifetime of the sigma hyperons. techniques used to obtain the spectra of Gifts that are a COMPLIMENT to receive! The xi-minus is 10 percent heavier than kaonic X rays.

110 •...,) ~ ..J ) .. } i

.------LEGAL NOTICE------~

This report was prepared as an account of work sponsored by the United States Government. Neither the United States nor the United States Atomic Energy Commission, nor any of their employees, nor any of their contractors, subcontractors, or their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness or usefulness of any information, apparatus, product or process disclosed, or represents that its use would not infringe privately owned rights. 4

TECHNICAL INFORMATION DIVISION LAWRENCE BERKELEY LABORATORY UNIVERSITY OF CALIFORNIA BERKELEY, CALIFORNIA 94720