Michael Friedlander CV/Published Papers

The decay at rest of a K-meson in which the secondary particle appears to be an electron of  90 Mev has recently been observed. The secondary particle, after traversing a distance of 2-3 cm in the emulsion, appears to have been sharply deviated ; thereafter, the track is closely similar to that of a slow electron. The grain density in the track, before and after the deviation, is indistinguishable from the ; plateau value '. The most plausible explanation of this behaviour is that it is due to the sudden loss of energy of an electron through the production of bremsstrahlung. Alternatively, the secondary particle could be assumed to be (a) a 77-meson which interacts with a nucleus and undergoes change exchange, the product nucleus subsequently sufferings-decay, or (/;) a/i-meson which decays in flight. The last two possibilities have been considered and appear very improbable.

Two examples of charged hyperons have been observed in photographic emulsions. One decays in flight, and its transformation may be re-presented Y± → L± + N0 + Q, the release of energy, Q being consistent with values obtained in other laboratories. In the other example, the secondary is a fast proton. This event may represent either the decay of a new type of hyperon or the nuclear capture of a negative hyperon.

Summary In a stack of stripped photographic emulsions, twenty events of type 2+0 n have been observed, in each of which the outgoing particles are a proton and a negative π-meson respectively; the latter particle was identified by the characteristic star it produced when brought to rest in the emulsion. Assuming that each of these events represents the decay in flight of a neutral hyperon according to the scheme Λ 0→π -+P+Q, values of the energy release Q have been calculated. In eleven of the events the proton could be traced to the end of its range; the energies of both particles could then be deduced using appropriate range-energy relations. In the remaining nine examples, the energy of the proton was deduced from grain density considerations and was accordingly less well determined.

This paper describes the preliminary results of a search for evidence of the nuclear interactions of negative heavy mesons. A qualitative analysis is given of the possible characteristics of their interactions and the appearance these might be expected to have in photographic emulsions. 37 ml. of emulsion, in which are recorded 10000 stars and 1200 slow π-mesons, have been completely examined. In the conditions of exposure, such a volume should contain six examples, with good geometry, of the decay of heavy mesons. Mass measurements have been carried out, by the range/scattering method, on 417 tracks of σ-mesons. In addition, 1800 σ-mesons, observed in 42 ml. of emulsion, have been examined. No disintegrations which can be attributed to heavy mesons have been found. The results suggest that some of the negative heavy mesons, on being brought to rest in photographic emulsions, behave in a manner qualitatively different from that of negative π-particles. Possible explanations for this result are suggested.

Summary:

Three examples of negative heavy mesons which produce nuclear disintegrations at the end of their ranges in emulsion, are described. Certain characteristics of the parent and capture stars of these mesons are discussed.

Details are given of six hyperon events observed in photographic emulsions. Two of these decay at rest into protons and giveQ-values of 115.8±1.0 MeV and 113.5±1.7 MeV for the assumed decay scheme: Y+ →p+π0+Q. Three others decay in flight; two giveQ-values 115±7 MeV and 103±10.5 MeV for the decay mode: Y±→n+π±+Q; the third is in agreement with the cascade type of decay: Y−→A0+π−+Q and has aQ=59±11 MeV. The sixth event has been interpreted as the interaction at rest of a negative hyperon; from the parent star of this hyperon there also emerges a K-meson.

Two events are described in which heavy mesons interact with nuclei in photographic emulsions, producing small stars and emerging themselves from the collisions. In one example, a relativistic singly charged particle enters the stack and produces a star with only three emergent charged particles, which have been identified as a hyperon, a π-meson and a K-meson respectively. The K-meson creates two stars before it comes to rest and decays with the emission of a slow μ-meson. In the other example, a K-meson enters the stack from outside and, after interacting, comes to rest within the emulsion and decays with the emission of a single lightly ionizing particle. Certain features of interest associated with the scattering properties of heavy mesons are discussed.

A large emulsion stack, exposed at high altitude, has been used to study the decaymodes of K-particles which produce a single charged secondary. The 5 decay modes, K μ , χ, ϰ and τ′ have been recognized from the nature and energy of the charged secondary. The masses of the parent particles of the two-body decay modes, K μ and χ found from the mean range of the charged secondary are (976±7) me and (969±3) me respectively. Independent values derived from measurements of the scattering of the secondary track near the decay point are (954±17) me and (972±15) me respectively. The reliability of these mass values is discussed. An examination of the relative frequency of the decay modes in these experimental conditions indicates that the K μ -and χ-modes constitute respectively about 67 % and 20 % of all the K-particle decays: the Kβ, ϰ- and τ′-modes being present to about 9 %, 3 %, and 1 % respectively.

Some predictions are made concerning the characteristics of the interactions produced by the nuclear capture of K−- and Y−-particles. It is assumed that the capture reaction is the inverse of the «associated production mechanism». A comparison is made between these predictions and the experimental data. The significant conclusions are: (i) the capture process sometimes involves two or more nucleons rather than a single nucleon; (ii) in view of the possible existence of Σ0-particles and their rapid transformation to Λ0-particles, the observation of Λ0-particles as end products of a capture process does not necessarily indicate that they were produced in the initial reaction; (iii) there appears to be an absence of μ-mesons of ∼ 120 MeV; this might indicate the production of a Σ0-particle instead of a Λ0-particle in the initial reaction or that the capture involves two or more nucleons; (iv) the available observations on capture stars are consistent with the general features of the theory of Gell-Mann and Pais.

During the course of scanning carried out in the G-stack, an event was observed which has been interpreted as the ejection of an unstable 4H1+ nucleus from a nuclear disintegration

Four examples of excited nuclear fragments will be reported here.

At the Padua Conference, the Rome group showed how hyperon events found in the course of scanning in photographic emulsions could be used to obtain an estimate of the mean lifetime of hyperons. The method was an extension of the statistical procedure introduced by BARTLETT for the analysis of Wilson chamber data, and was designed to utilise to the full the rather poor number of events then available. Since the detection probability of a hyperon decay event is a function of the hyperon velocity, when it is found by scanning, the method involved corrections for scanning bias. However, in the course of several experiments by different groups at Bristol, 14 hyperons have been found in a completely unbiassed way. It has been possible to use these to obtain a lifetime estimate free from the disadvantage of using corrections for scanning bias which are rather difficult to estimate accurately.

During the course of scanning in the Bristol and Padua sections of the G-stack, 22 capture stars produced by the nuclear interaction of K--mesons at rest have been found. The details of these, together with those of seven other events found in Sardiniau stacks exposed to the cosmic radiation, are given in Table I. In this communication we discuss the results of some speculations on the production and interaction of the K- particle on the basis oi a combination of these new data with 16 other published events found in cosmic ray exposed stacks. Further, it appears of value in considering the mean life time and production of K--mesons to compare the cosmic-ray observations with the results reported at this meeting [1-3] on the K--particles produced at the Bevatron.

CONTENTS 1. Introduction (C. F. POWELL). 2. The Ku decay (reported by M. MERLIN). 3. The x-decay (reported by C. O'CEALLAIGH). 3a. Unusual decay of a x-meson (reported by D. KEEFE, on behalf of the University College, Dublin group), 3b. A determination of the mass of a x-meson by the analysis of a collision of its secondary with a proton (M. DI CORATO and L. SCARSI, reported by M. DI CORATO). 4. The X- and Kb-particles (reported by M. W. FRIEDLANDER) 5. On the composition of the K-particle decay spectrum (reported by A. BONETTI).

In the course of an investigation, in which stopped  -mesons were traced back to their origins within a stack of stripped emulsions, one hyperfragment was found (+). This event may be identified with the hyper-triton, first reported by BONETTI et al. (1); the point of interest in this particular case is that the fragment has undergone decay in flight. A closely similar event has recently been reported by SKJEGGESTAD and SORENSON (2).

Since the original observation of BONETTI et al. (1), there have been reported 14 examples of the mesonic decay of 3HA hyperfragments. Most of these fragments decayed after coming to rest, but two of the decays occurred while the fragment was still in flight. We may therefore estimate the lifetime for the me3onic decay of 3H A particles.

Summary. - - A comparison was made between the ranges of artifiei:flly accelerated protons in Aluminium and in Ilford G5 photographic emulsion. The ranges in emulsion were obtained by direct measurements along the particle tracks, and those in Aluminium by an attenuation method. The ranges of protons of three different energies were 19.31, 13.23 and 7.82 g/cm2 in Aluminium, and 22.85, 15.58 and 9.50 g/cm2 in emulsion of density 3.791 g/cm3 conditioned to 58% relative humidity. The corresponding energies were 146.5 MeV, 117.9 MeV and 87.4 MeV. Assuming the range-energy relation for protons to be at present better determined for Aluminium than for photographic emulsion, this experiment provides new information concerning the relation between particle range and energy in nuclear emulsion.

3ummary. - - A study has been made of the parent stars of K-mesons produced by the Cosmic Radiation. Emission angle and energy spectra are given for these mesons, together with a distribution of star sizes. An estimate is made of the frequency of occurrence of associated hyperons, other K-mesons and hyperfragments. Three particularly interesting events are described, including one which has enabled the mass of the negative E-hyperon to be calcu!ated as 2344 +/- 6 m(sub-e).

Summary. - - A systematic investigation has been carried out, using nuclear photographic emulsions, into the production of heavy unstable particles by Pi---mesons of 4.5 GeV/c. From 2 854 stars, 4 hyperons and 4 heavy mesons were found which had velocities of less than 0.7c, and which satisfied certain geometrical selection criteria. One hyperon produces a secondary Pi-meson which comes to rest in the emulsion stack. The mass of this hyperon, shown to be negatively charged by the nuclear capture of its secondary particle, is (2352 +/- 5) m(sub-e).

Numerical values have been calculated for the scattering constant for multiply charged particles in photographic emulsion. The constant has been calculated both with and without cut-off being applied for correction for single scattering, and the results are presented in graphical form.

ERRATA Figs. 1 and 2 illustrate the variation of scattering constant with cell-size and velocity for protons and a-particles. The labelling of the curves with respect to velocity has been inverted: the curves labelled beta=l.0 should be labelled beta=0.5, and vice versa for the curves labelled beta=0.5.

Summary. - - The primary cosmic-ray a-particle energy spectrum has been investigated, using photographic emulsions flown from Minneapolis on July 30th, 1957. The total flux observed was (151 +/- 9)particles/cm2 sr s. The differential energy spectrum shows a broad maximum between 400 and 600 MeV/nucleon, and appears different in shape from the spectrum observed at solar minimum. No particles were observed to have kinetic energies below 200 MeV/nucleon, but a substantial flux was observed between 200 and 300 MeV/nueleon. From the centered dipole approximation to the geomagnetic field, one would expect a cut-off energy at this latitude of 292 MeV/nucleon. The results presented here are in disagreement with this figure, but do not allow a choice to be made between cut-off energies predicted from other models.

In a recent issue of Science [133, 2000 (1961)] there appears an article by Howard Margolis about the separate reports on Project Chariot (the AEC proposal for underground explosions at Cape Thompson, Alaska) issued by the AEC and by the St. Louis Committee for Nuclear Information (CNI). Margolis' comments on the CNI report comprise the following items: (i) a summary of the contents of the report; (ii) an account of supposed "technical errors" (only one is mentioned) in the report and Margolis' criticism of certain of its conclusions; (iii) Margolis' own statement regarding the relative risks to Alaska Eskimos from radiation due to television watching, current levels of fallout, and the fallout that might result from Project Chariot. In our opinion Margolis' discussion of the contents of the CNI report is incomplete, inaccurate and misleading.

A stack of 154 30cm by 16cm 600u Ilford G5 emulsions has been exposed for 10 hours at an altitude of  4g/cm2 over Texas. These emulsions wer interleaved with 500u thick sheets of polythene and teflon. The purpose of the experiment is to study the characteristics of the nuclear interaction produced by the heavy, Z>= 3, nuclei of the primary cosmic radiation, as they pass through these sheets of plastic material. Those interactions in the teflon should resemble those produced in air, while the differences between the characteristics of the interactions in the two types of plastic should be indicative of the effects of the hydrogen nuclei.

At the present time, whie preliminary data are available from this experiment, we do not feel that they are in a form suitable for publication since they might be subject to later revision. Instead we will merely give an estimate of the statistical weight of the data that should be available eventually. It is intended to detect 10^4 nuclei with Z>=6 which enter the stack. Of these we expect 30% to escape without interacting and of the remaining 7000, 4000 to interact in emulsion, 1800 in polythene, and 1200 in teflon.

In high-altitude balloon flights over North America, nuclear emulsions were used to study the characteristics of the primary helium nuclei in cosmic radiation. On Feb. 8, 1959, at 41 deg N the helium-nuclei flux was found to be 76 plus or minus 4 particles/m/sup 2//sterad/sec. On Aug. 3, 1958, it was 88 plus or minus 8 particles/m/sup 2//sterad/sec at 49 deg N and 135 plus or minus 8 particles/m/sup 2// sterad/sec at 61 deg N. (A.G.W.)

Nuclear photographic emulsions were exposed to the cosmic radiation on a high altitude balloon flight at 49^o N geomagnetic latidude on 3rd August 1958. The total flux of primary alpha-particles, having kinetic energies greater than 400 MeV/nucleon, was found to be (87±8) particles/m2 ster s. Simultaneously, another set of emulsions was exposed at 61^o N geomagnetic latitude. A comparison of the data obtained from the two nights leads to an estimate of the geomagnetic cut-off for 49^o N as (500±50) MeV/nucleon kinetic energy.

The interaction and absorption fragmentation parameters and mean free paths of heavy, Z>=3, cosmic ray nuclei have been measured in polyethylene (CH2)n and teflon (CF2)„. Within the statistical accuracy of these results it has been shown that previously deduced values of the fragmentation parameters in the atmosphere were essentially correct, as were the mean free paths. Tentative values have been deduced for the fragmentation parameters in hydrogen and these have been compared with those assumed previously. The significance of these results is discussed.

Nuclear explosions can move great quantites of earth and will prove useful IF preliminary studies for each excavation are thorough, and IF such studies show that the biological risk is small, and IF this risk is acceptable to the people who may be affected, and IF adequate safety precautions are taken.

Cosmic ray nuclei have been observed with the use of plastic track-detecting solids in satellites and high-altitude balloon flights. Nuclear emulsions in the stacks of plastic sheets allowed the positive identification of cosmic ray nuclei as light as nitrogen. The most striking new information was the failure to observe relativistic iron nuclei, a result which has led to an advance in the understanding of track registration criteria.

The flux of primary cosmic-ray helium nuclei was measured in nuclear photographic emulsions exposed on a high altitude balloon flight in Texas, in April 1965. The flux value derived was 110 +/- 8 particles/m^2/sec. ster, substantially in excess of that expected on the basis of data obtained in 1954-6, at the time of the previous minimum in solar activity. A re-examination of published records of older flights shows that the geomagnetic cut-off values assumed were in error. Discussions of solar modulation effects in the high energy regions will require modification.

Prepared at the request of the AAPT Committee on Resource Letters; supported by a grant from the National Science Foundation. This is one of a series of Resource Letters on different topics, intended to guide college physicists to some of the literature and other teaching aids that may help them to improve course contents in specied fields of physics. No Resource Letter is meant to be exhaustive and complete; in time there may be more than one letter on some of the main subjects of interest. Comments and suggestions concerning the content and arrangement of letters as well as suggestions for future topics will be welcomed. Please send such communications to Professor Joel E. Gordon, Resource Letter Committee, Department of Physics, Amherst College, Amherst, Massachusetts 01002. Notation: The letter E after an item number indicates elementary level, useful principally for high school and introductory college use; the letter I indicates intermediate (junior, senior) level; and the letter A indicates advanced material, principally suited for senior, graduate study. An asterisk ( *) indicates items particularly recommended for introductory study.

Nuclear swords have not yet been beaten info plowshares. The “Plowshare” program of the Atomic Energy Commission has chugged along far behind the military uses of nuclear energy; it has not become a substitute for it.

The most recent vehicle in the Plowshare Program is called the Gasbuggy. Most Plowshare projects have names suggesting thta they are going somewhere. but how far they will get is uncertain. The Gasbuggy bang shook the New Mexico desert on December 10, 1967 to the accompaniment of much optimistic press comment. But the facts are not in yet, and it is too soon to cheer for a new era in the use of atomic power.

In a recent publication (Friedlander and Klarmann, 1967), attention was drawn to the need for greater care in specifying the geomagnetic cut-off appropriate to high altitude balloon flights for observations of the primary cosmic radiation. In that paper, an apparently high vahre of the flux of He-nuclei could be satisfactorily explanted m terms of the geomagnettc cut-off, and when older data, published over the years by many groups, were re-examined, a greater measure of internal consistency could be obtained.

We wish to report now a value for the flux of heavier particles, i.e. those with Z > 3, obtained from examination of the same set of nuclear photographic emulsions as was used for the He-nuclei. The balloon flight was on April 24th, 1965, launched from Palestine, Texas. The flight trajectory corresponds to a mean geomagnetic cut-off of 4-5 GV rigidity or 1.5 GeV/nucleon kinetic energy for multiply charged particles, (Quenby and Wenk, 1962) and so attention is restricted to particles havmg at least this energy. We have found the flux of particle with Z > 3 to be J (Z > 3) = 11.5 +/1 0.5 particles/m^2.sec.ster, which is considerably higher than had been expected on the basis of data obtained during the previous period of low solar activity.

The effects of fallout from nuclear weapons explosions have been of concern to the Committee for Environmental Information (CEI), publisher of Environment, since its founding. Over the years we have maintained this interest and have published articles covering a variety of aspects of this problem: the effects of radiation on men, animals, and plants; the production of radioactive isotopes; and the different paths by which these isotopes may be carried in our environment and into our foods. Recently we have received a large number of requests to comment on the claims of Dr. Ernest Sternglass, of the University of Pittsburgh, that fallout from atmosphereric tests of nuclear explosives is responsible for an appreciable fraction of the fetal and infant mortality in this country. It is clearly appropriate for Environment to review this subject and bring our readers up to date. A presentation of Dr. Sternglass' position follows this article.

Interleaved layers of nuclear photographic emulsion and plastic detectors, covering a total area of 21 m2, were exposed to the primary cosmic radiation on high-altitude balloon flights. Flux values, in particles/m2 sr sec, have been estimated to be J(Z> 33)> 2.6×10−5, J(33< Z< 40)< 1.9×10−5, J(Z> 70)≳1×10−6. These values refer to the top of the atmosphere, after extrapolation through 1.5 g/cm2 of detector and 3.5 g/cm2 of atmosphere, for particles with magnetic rigidities above 5 GeV.

Using the fragmentation parameters deduced by Turner, calculations have been performed for the propagation of very heavy cosmic ray particles, i.e., those with Z > 33. Comparison is made with the experimental results now being obtained.

Cosmic ray particles with Z > 40 have been identified by their tracks in interleaved nuclear photographic emulsions and plastic detectors. Preliminary results will be presented from high altitude balloon flights of 40 hr duration, which carried a total detector area of 20 m^2.

Two large stacks of nuclear photographic emulsions were exposed to the primary cosmic radiation on a high altitude balloon flight over Palestine, Texas on April 24, 1965, during the period of minimum solar activity. The intensities of the fluxes of the groups of heavy particles having rigidities above about 4.3 GV were found to be: L-nuclei (3 <= Z <= 5) 2.2 +/- 0.4 particles/m^2.ster.sec, M-nuclei (6 <= Z <= 9) 6.8 +/- 0.7 particles/m^2.ster.sec, H-nuclei (Z >= 10) 2.5 +/- 0.3 particles/m^2.ster.sec. From these, the L/M ratio is derived as 0.32 +/- 0.07. Ah values refer to the top of the atmosphere, having been extrapolated from the flight altitude of 2.7 g/cm^2. The relative abundances of the elements within the L group have also been estimated.

Four sources of apparent flux  10^-13 W cm^-2 and angular size <0.5 deg were detected in the wavelength region between 45 and 250 u during a sky survey with a balloon-borne telescope at an altitude of 28 km. The source positions are not uniquely identifiable with sources prominent in other spectral regions.

The results of preliminary measurements on the track of a primary cosmic ray particle, in emulsions and plastics, indicated a possible charge of Z = 113. (Blanford, et al., 1969). Further measurements and calibration have shown that this particle was not relatvistic within our detectors, and the best charge estimate is Z = 76 +/- 4. During a total of five balloon flights, an exposure of about 10^7 m^2.ster.s has been accumulated, with no particles being detected in the charge range Z > 96. Combining this with the data reported by other workers, allows estimates to be made of the flux of such particles, and their abundance relative to iron nuclei.

Four sources of apparent flux  10^-13 W.cm^-2 and angular size < 0.5 deg were detected in the 45 - 250 micron wavelength region during a sky survey with a balloon-borne telescope at 28km altitude. The source positions are not uniquely identifiable with sources prominent in other spectral regions.

This book was designed to be a useful adjunct to any introductory science course. Topics included have been tested in a course for nonscience students. The author's objective is to provide students with a basic understanding of the workings of science and its relationship to society. Ten chapters are included: The Social Direction of Scientists; Spreading Scientific Information; Certainty and Authority in Science; Controversy: The Resolution of Scientific Conflicts; Organized Science--New Roles and Decisions; The University: A Home for Research; The Application of Science: Relevance; Science and Government; Values, Priorities, and Choice; and Responsibilities and Obligations. The book also contains a lengthy appensix; a bibliography of books, resource letters in physics, periodicals, and recent publications; and an index. (PEB)

We present evidence for the existence of a hitherto unrecognized flux of nuclei of a charge of 6 ≲ Z ≲ 26 and kinetic energies of <150 Mev/nucleon at 4 g/cm² residual atmosphere over Texas (41^oN geomagnetic). The flux observed at the balloon-borne detector is (2.3 ± 0.5) × 10−5 particle/m² ster sec, which is comparable in intensity to the flux of primary cosmic-ray nuclei having Z > 35. This flux is in qualitative agreement with estimates of the flux expected from re-entrant albedo, produced by interactions of primary Fe group nuclei in the atmosphere. We consider the implications of these findings for observations of the flux of very heavy primary cosmic-ray nuclei.

In an attempt to match the observed charge spectrum of VVH particles, several source spectra have been constructed from combinations of r- and s-process nuclei. Their propagation has then been followed, allowing for interactions and decay, and comparisons have been made between the calculated near-Earth spectra and those observed during high altitude balloon flights. None of the models yet used leads to good agreement with observation, suggesting either that more complicated models need to be examined, or that different components (for instance the r- and s-process nuclei) have different histories.

For comparisons between theoretical and observed charge spectra of the VVH particles to be meaningful, at least two conditions must be met. First, charge resoluton must be adequate to separate important groups of nuclei, and there should be no significant systematic errors in the charge scale developed. Interactions of VVH particles that we have observed gave us confidence in the charge scales. Second, there must be adequate rejection of slower particles of smaller Z, which have been observed in several flights. Within these conditions, it has been shown that observed features of the charge spectrum are not accidents of the analysis but reflect real variations in the relative abundances that must be explained by any successful model.

Large areas of nuclear emulsions and plastic detectors were exposed to the primary cosmic radiation during high altitude balloon flights. From the analysis of 141 particle tracks recorded during a total exposure of 1.3 x 10^7 m^2.ster.sec, a charge spectrum of the VVH particles has been derived.

Large areas of plastic detectors and nuclear emulsions were exposed to the primary cosmic radiation on two high-altitude balloon flights in May 1968 and September 1969. From measurements on the tracks found in the scanning of the plastic detectors, events with charges Z > 50 were selected, and these data were consolidated with those from our earlier flights. Several conclusions can be drawn from the observed charge spectrum. The detection of trans-bismuth nuclei confirms earlier observations of these particles in the cosmic rays. However, no trans-uranium particles were observed. Detailed features of the charge spectrum cannot be explained by nuclei from r-process nucleosynthesis alone. Although the addition of particles following s-process abundances yields improved agreement, the spectrum appears more complicated than would result from a simple combination of r- and s-process abundances with identical propagation histories.

Tracks of very heavy cosmic-ray particles have been recorded in nuclear emulsions and several different types of plastic detectors exposed during two high-altitude balloon Qights in September 1968. Based on a total of 113 tracks, the following flux values have been derived for kinetic energies &1 GeV/nucleon: J(35 <= Z <= 40) = (16+/-4) x 10^-6 particles/m^2 sr sec, J(41 <= Z <= 50) = (28 +/- 6) x 10^-6 particles/m^2 sr sec, J(51 <= Z >= 60) = (9 +/-2) x10^-6 particles/m^2 sr sec, J(61<= Z >= 70) = (1.8 +/- 0.7) x10^-6 particles/m^2 sr sec, J(71 <= Z >= 85) = (3 +/- 1) x10^-6 particles/m^2 sr sec, J(Z >=86) = (1.0+/- 0.6) x 10^-6 particles/m^2 sr sec. The well-established presence of particles with Z >= 86 requires a cosmic-ray source in which the r process of nucleosynthesis has been effective. The relative abundances over the charge region (51<= Z <= 85) show agreement with solar-system abundances, but there appear to be significant departures for the two lower-charge groups. Calibration of the detectors and experimental problems are also discussed.

Localized sources of far infrared radiation (approximately 50 microns) have been detected during a high altitude balloon flight with a 40 cm telescope and silicon detectors. The flight system is described and preliminary results are presented.

During a high-altitude balloon flight, sources of far-infrared radiation have been detected with apparent fluxes >3 X 10^-12 W cm^-2 in the spectral band 50-500 mu. While the sources are not uniquely identifiable with any well-known class of celestial objects, two associations should be noted. Many of the objects lie close to local stars; there is also a tendency to cluster around the ecliptic plane. Alternatively, a new class of celestial objects may have been observed.

Your editorial “Good for people, bad for science” (July 10) requires a prompt comment, for you apparently advocate a major change in the system of academic tenure. At the same time, your editorial seems to indicate neither an awareness of the complexity of the issue, nor of experience with alternative tenure systems, nor of the considerable literature in this area; I refer here primarily to the tenure system that is very widely used in the USA, the role of the American Association of University Professors (AAUP), and the many articles and books in which this subject is discussed.

It is shown that the cosmic-ray event recently interpreted as the track of a Dirac monopole can instead be plausibly described in terms of the interaction of an ultraheavy cosmic-ray nucleus, having Z  96 and velocity  0.72c.

For the 25 years since Worlds in Collision was published, Immanuel Velikovsky has awaited the recognition and acceptance that he feels he justly deserves. Whatever recognition he has achieved has come from outside the scientific community; the vast majority of professional scientists has either not examined his work, or has rejected it with varying degrees of vehemence. Those scientists who have reviewed his earlier works (Worlds in Collision and Earth in Upheaval) have been sufficiently negative in their assessments as to deter the scientific community at large from any extended consideratioa During these 25 years, the scientific community has been under intermittent attack for its alleged failure to give Velikovsky a fair hearing and his theories a fair test As early as 1950, some scientists brought pressure on his publishers, the Macmillan Company, that led to Macmillan transferring the publication of Velikovsky's books to other publishers who did not have text-book divisions through which they were laid open to threats of boycott in the large academic market. This particular episode has coloured all later discussions of Velikovsky and his theories; it has and probably will continue to re-emerge and haunt the scientific community and while it can possibly be understood in some ways, it can or should in no way be condoned But, no matter how reprehensible that occurrence was, it cannot be taken as lending any strength to the intrinsic merits of Velikovsky's theories, even though some of his supporters have attempted to draw this kind of inference.

Cosmic ray particles with kinetic energies well below cutoff values were detected during a high-altitude balloon flight at 41^oN geomagnetic. These particles had kinetic energies up to 400 MeV/amu and charges in the range 6 ≤ Z ≤ 30. They are probably reentrant albedo particles and are of interest primarily because they can be confused with fast, ultra-heavy primary particles in some experiments.

Eugene Feenberg, emeritus Wayman Crow Professor of Physics at Washington University, St Louis, and member of the National Academy of Sciences, died on 7 November at the age of 71. In a distinguished career of theoretical research spanning five decades, Feenberg made fundamental contributions to nuclear theory, approximation methods and the theory of quantum fluids. He was one of the pioneers in the application methods and the theory of quantum mechanics to nuclear structure.

Mayr's comments on tenure require a prompt response. They appear to offer a sensible and easily implemented solution to the problem posed by incompetent but tenured faculty. Unfortunately, however, while Mayr tries to preserve some of the protection afforded by tenure, his proposal needs to be vigorously resisted, for it would more probably lead to an undermining of tenure without necessarily bringing the benefits he seeks.

Astronomy is probably the oldest science. In even the oldest written records, such as the cuneiform tablets from Babylonia, we find records of movements of the Moon and Venus that represent many years of careful observing. At least as old as these tablets are the circles of standing stones, such as Stonehenge, whose planning attests to surprisingly sophisticated awareness of subtle features in the movement of the Sun and Moon.

Within the past few decades, there has been a growing collaborative interest among astronomers and archaeologists in what is now termed archaeoastronomy. This new discipline covers all aspects of ancient astronomy, which was largely directed to observing the rising and setting of bright objects. While Stonehenge is by far the best known of these megalithic structures, we are now finding worldwide evidence of the acuity of ancient observations.

Dust formation is a process which occurs in many astrophysical environments, yet is not fully understood. We have developed a kinetic approach for grain nucleation based on the suggestions of Donn et.al. (1981) who use the Kassel theory of unimolecular reaction rates to estimate the atomic sticking coefficients. This is being applied to carbon-rich novae. Our preliminary calculations show that without some inhibiting factor, the number of nucleation sites is so high that the grains produced are small, a few hundred angstroms in size. Recent infrared and visible light data suggest the presence of grains a few tenths to a few microns in size. We have developed a model in which the temperature fluctuations of the tiny clusters is taken into account. In this approach, the arrival of photons is treated as a Poisson process, while the cooling rate is proportional to the energy of the cluster. A probability distribution for the cluster energy is derived for a given photon flux and the evaporation rate is obtained· from it using the Kassel theory. The fluctuating temperature leads to an increased mean evaporation rate which decreases the number of nucleation sites and hence increases grain size.

I always enjoy Professor Mozart's offbeat observations and tendentious manifestos, as well as the more cautious suggestions of his medium David Mermin, who is lucky to have such an interesting visitor. (We never see any "Mozarts" out here in the Midwest, though I think Elvis occasionally visits Urbana discount stores.) Regarding the Reference Frame discussion on the physics seminar (November 1992, page 9): I have seen enough worthy talks in my few years to know the situation is far from hopeless, yet I couldn't help but recall some of the worst talks I have ever seen.

Dust is observed to form in nova ejecta. The grain temperature is determined by the diluted nova radiation field rather than the gas kinetic temperature, making classical nucleation theory inapplicable. We used kinetic equations to calculate the growth of carbon nuclei in these ejecta. For expected values of the parameters too many clusters grew, despite the small sticking probability of atoms to small clusters, and the clusters only reached radii of about 100 Angstrom when the carbon vapor was depleted. We then included the effects of cluster photodissociation by ultraviolet radiation from the nova. This suppresses nucleation, but too well, and no grains form at all. Finally we suggest that a few growing carbon nuclei may be protected from photodissociation by a sacrificial surface layer of hydrogen.

Eta Car is surrounded by a thick shell of dust whose infrared emission is close to 5 x 10 exp 6 solar luminosities. We propose a new model for Eta Car in which cosmic rays originate in a central object and stream out, losing energy in the gas and dust. This energy is subsequently radiated by the dust grains, with most of the energy coming from cosmic-ray protons having kinetic energies from 1 MeV to 10 MeV. Assuming for the cosmic-ray protons a differential kinetic energy spectrum of the form E exp -2.5, the infrared spectrum can be very well fitted for wavelengths between 5 and 175 micron. The visual continuum exhibits features that strongly suggest the synchrotron mechanism. Tests of the model are provided through predicted fluxes of high- and low-energy gamma rays that will be produced through proton collisions in the gas and dust of the nebula.

Course reaches nonscience students with everyday life applications

The observation of intense gamma-ray line emission from the Orion complex, attributed by Bloemen et al. to de-excitation of cosmic-ray carbon and oxygen nuclei, has important implications for emission from Orion in the infrared and in high-energy gamma-rays, and also for the theories of cosmic-ray origins. Some of these implications are briefly pointed out.

The observation of intense gamma-ray line emission from the Orion complex, attributed by Bloemen et al. to de-excitation of cosmic-ray carbon and oxygen nuclei, has important implications for emission from Orion in the infrared and in high-energy gamma-rays, and also for the theories of cosmic-ray origins. Some of these implications are briefly pointed out.

This collection of tributes provides a very welcome opportunity to take note of one of our most effective but very quiet defenders of academic freedom, R. Dale Swihart. Almost thirty years ago, we were colleagues on the Executive Committee of the Washington University chapter of the American Association of University Professors (AAUP). It was a time when the inadequacy of Washington University's old tenure policy was clear. Chancellor Tom Eliot asked our AAUP chapter to undertake the initial drafting of a new policy and, of course, it was Dale who did this writing. The draft went through rigorous review by our committee, by the Faculty Senate Council and the Administration and, finally, by the Board of Trustees before adoption in May 1974. Though there have been several amendments and additions over the years, the fundamental framework still stands-it has worn well, a tribute to both its soundness and the general will of most (if not all) people to abide by its spirit as well as its letters.

Martin Kemp writes that “the details of Galileo's cratered Moons are difficult to align precisely with actual features”1. I would like to draw readers' attention to the work of Ewen Whitaker2, a selenographer at the University of Arizona. Whitaker reviewed earlier efforts at identifying the features drawn by Galileo, and took special note of the important contributions of Guglielmo Righini, Owen Gingerich and Stillman Drake. He provided side-by-side comparisons of Galileo's drawings with modern photographs taken at the same lunar phases, and these provide striking support for his contention that Galileo did indeed observe, and record, very accurately.

Enigmatic for many years, cosmic rays are now known to be not rays at all, but particles, the nuclei of atoms, raining down continually on the earth, where they can be detected throughout the atmosphere and sometimes even thousands of feet underground. This book tells the long-running detective story behind the discovery and study of cosmic rays, a story that stretches from the early days of subatomic particle physics in the 1890s to the frontiers of high-energy astrophysics today.

Writing for the amateur scientist and the educated general reader, Michael Friedlander, a cosmic ray researcher, relates the history of cosmic ray science from its accidental discovery to its present status. He explains how cosmic rays are identified and how their energies are measured, then surveys current knowledge and theories of thin cosmic rain. The most thorough, up-to-date, and readable account of these intriguing phenomena, his book makes us party to the search into the nature, behavior, and origins of cosmic rays---and into the sources of their enormous energy, sometimes hundreds of millions times greater than the energy achievable in the most powerful earthbound particle accelerators. As this search led unexpectedly to the discovery of new particles such as the muon, pion, kaon, and hyperon, and as it reveals scenes of awesome violence in the cosmos and offers clues about black holes, supernovas, neutron stars, quasars, and neutrinos, we see clearly why cosmic rays remain central to an astonishingly diverse range of research studies on scales infinitesimally small and large.

Attractively illustrated, engagingly written, this is a fascinating inside look at a science at the center of our understanding of our universe.

Eugene Feenberg, emeritus Wayman Crow Professor of Physics at Washington University, St Louis, and a member of the National Academy of Sciences, died on 7 November at the age of 71. In a distinguished career of theoretical research spanning five decades, Feenberg made fundamental contributions to nuclear theory, approximation mathods and the theory of quantum fluids. He was one of the pioneers in the application methods and the theory of quantum mechanics to nuclear structure.

Excavations by Warren Wittry and others at the Cahokia Mounds State Historic Site in Illinois have revealed traces of posts that had been set out around five large circles. The most complete of these circles had a radius of 205ft. and contained posts that were aligned in the directions of the equinox and solstice sunrises. This paper reports the coordinates of all posts as measured by Wittry, as well as the astronomical alignments that are then calculated. The possibility that the alignments are not intentional but are instead the products of chance is examined but not supported.

Richard E. Norberg was an innovator in nuclear magnetic resonance (NMR), with a productive research career spanning more than 50 years. He died 20 April 2010 in Saint Louis, Missouri, after a brief period of declining health.

I was very interested in Robert P Crease's article about levels of significance in discoveries (“Discovery with statistics”, August p19). Before the mid-1950s, when accelerators with energies above 1 GeV came online, a vigorous part of cosmic-ray research involved exploring the unexpected “elementary” particles that left their tracks in photographic emulsions and cloud chambers.

High-energy nuclei coming from far beyond the Solar System, and the exotic particles they produce, remain our best window onto the extreme Universe. Michael Friedlander reflects on what we have learned.

Scientific discoveries are constantly in the news. Almost daily we hear about new and important breakthroughs. But sometimes it turns out that what was trumpeted as scientific truth is later discredited, or controversy may long swirl about some dramatic claim. What is a nonscientist to believe? Many books debunk pseudoscience, and some others present only the scientific consensus on any given issue. In At the Fringes of Science Michael Friedlander offers a careful look at the shadowlands of science. What makes Friedlander's book especially useful is that he reviews conventional scientific method and shows how scientists examine the hard cases to determine what is science and what is pseudoscience. Emphasizing that there is no clear line of demarcation between science and nonscience, Friedlander leads the reader through case after entertaining case, covering the favorites of "tabloid science" such as astrology and UFOs, scientific controversies such as cold fusion, and those maverick ideas that were at first rejected by science only to be embraced later. There are many good stories here, but there is also much learning and wisdom. Students of science and interested lay readers will come away from this book with an increased understanding of what science is, how it works, and how the nonscientist should deal with science at its fringes.