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The Hyperon Bubble Chamber, HYBUC, was a 50 Hz rapid cycling 30 cm. high precision hydrogen chamber. HYBUC was the only successful high field chamber and its superconducting magnet was operated at fields over 11 T for more than 5000 hours at CERN. The current world averages for the sigma magnetic moment, lifetime and Σ decay parameters make extensive use of the HYBUC data. This lifetimes data also showed that elementary particle clocks are invariant to intense longitudinal acceleration.

Measurements of bioluminescence have been made at depths of about 4500 m with (1) freely falling, (2) ship-suspended and (3) bottom anchored instruments. A comparison of these measurements shows that most of the light recorded by ship-suspended measurements at great depths is bioluminescence stimulated by the motion of the ship on the surface translated to the detector at depth. Most of the light observed in all of these measurements is from flashes. An estimate of the intensity distribution of source brightness of flashes is presented. The observed flashes were produced more frequently within a few meters of the detector than in an equal volume of water at greater distance in the ocean.

A string of seven optical detectors deployed from a ship was used to detect the Cherenkov light from muons at ocean depths ranging from 2000 to 4000 m in intervals of {similar to}500 m. The flux and angular distributions of cosmic-ray muons were measured. An effective area for fivefold coincidences of 420 m{sup 2} for downward-going muons was achieved. The results are consistent with those derived from underground observations and theoretical calculations. The measured vertical intensity ranges from (9.84{plus minus}6.5){times}10{sup {minus}8} cm{sup {minus}2} s{sup {minus}1} sr{sup {minus}1} at 2090 m of water equivalent (mwe) to (4.57{plus minus}1.37){times}10{sup {minus}9} cm{sup {minus}2} s{sup {minus}1} sr{sup {minus}1} at 4157 mwe.

A measurement of cosmic ray muon flux was obtained at ocean depths ranging from 2 km to 4 km at 500 m intervals off the West Coast of the Big Island of Hawaii. A brief description of the experiment and the results will be presented in this paper.

The scientific goals, design, capabilities, and status of the DUMAND II detector system are described. In June, 1989, the High Energy Physics Advisory Panel recommended support for construction of DUMAND II to the U.S. Department of Energy. Funding began in 1990, and prototype development for various detector subsystems is under way. Current plans include deployment of the shore cable, junction box and three strings of optical detector modules in 1992, and expansion to the full 9‐string configuration in 1993.

We present evidence for the existence of two new $I=0$ scalar mesons [${g}_{s}(1240)$ and ${S}^{*\ensuremath{'}}(1730)$] from an amplitude analysis of the reaction ${\ensuremath{\pi}}^{\ensuremath{-}}p\ensuremath{\rightarrow}{K}_{S}^{0}{K}_{S}^{0}n$ at 23 GeV/c. An examination of the mass splittings present shows that neither of these states can be easily assigned to a (near) ideally mixed ${J}^{\mathrm{PC}}={0}^{++}$ nonet. These results are in qualitative agreement with recent theoretical predictions of glucon-glucon bound states.

K ∗± (892) production is studied in the reaction π − N → K S 0 K S 0 + X where X includes up to five observed charged particles. An excess of K ∗− over K ∗+ is observed for Feynman- x > 0.1. The ratio of K ∗+ to K ∗− decreases with x as predicted by QCD counting rules. K S 0 and K ∗ production are compared to recent D and D ∗ data from other experiments.

We present data on\(\bar pn\) and π− n collisions obtained from an exposure of the 30′' FNAL deuterium filled bubble chamber to a mixed\({{\bar p} \mathord{\left/ {\vphantom {{\bar p} {\pi ^ - }}} \right. \kern-\nulldelimiterspace} {\pi ^ - }}\) beam with a momentum of 100 GeV/c. We find that in 17±2% of the collisions with the antiproton there is an interaction on the spectator while for the collisions with π− mesons the corresponding number is 15±2%. The\(\bar pn\) and π− n multiplicity distributions have average charged multiplicities of 6.46±0.07 and 6.53±0.08 respectively. The average multiplicities for both types of interactions are slightly smaller than those for the corresponding reactions on hydrogen by an amount that is the same as observed at other energies. As an estimate of\(\bar pn\) annihilation we have calculated the difference\(\sigma _n (\bar pn) - \sigma _n (pn)\) for each prong numbern. We find an average multiplicity of 9±1, a value close to that for\(\bar pp\) annihilation at the same energy. combining our data with lower energy\(\bar pn\) annihilation data, we observe that the average negative multiplicity is systematically larger than that for\(\bar pp\) annihilation similar to the difference between neutron and proton target data with other beam projectiles.

The vertical profile of bioluminescence at a station hear Hawaii has been measured to a depth of 4300 m using a calibrated instrument with a threshold sensitivity of 400 photons cm −2 s −1 . The measured light is dominated by flashes over a very faint ambient background. The median light levels follow an exponential scaling law below 2000 m and decrease at the rate of 1/e per kilometer. Stimulated bioluminescence is observed in the wake of the instrument, even at depth.

In an experiment using the Fermilab Multiparticle Spectrometer we have studied forward production of high mass events containing two strange particles and charged pions. In the final state ΛK s 0 π + π + π − π − we observe 5 events with effective mass above 5.5 GeV/ c 2 . Four of these events cluster near 5.75 GeV/ c 2 , and three of these events contain K s 0 π + π − mass combinations consistent with the charmed D 0 .

Forward K/sub S//sup 0/K/sub S//sup 0/ production (x/sub F/>0.2) with an associated charged multiplicity of five or less has been observed in an experiment designed to trigger on two neutral strange particles. The K/sub S//sup 0/K/sub S//sup 0/ mass distribution shows f/sup 0/(1270), A/sub 2/(1320), f'(1515), and S('(1730) production with cross sections/nucleon for x/sub F/>0.2 of 49 +- 17, 54 +- 15, 1.4 +- 0.4, and 0.6 +- 0.2 ..mu..b, respectively. The differential cross sections indicate central production of the S((975), whereas the f/sup 0/(1270), A/sub 2/(1320), f'(1515), and S('(1730) have a sizable leading component. Inclusive K/sub S//sup 0/ production in this data sample is described by a (1-x/sub F/)/sup 1.6/ distribution in qualitative agreement with simple quark-counting rules. Both the K/sub S//sup 0/K/sub S//sup 0/ and single-K/sub S//sup 0/ p/sub T/ /sup 2/ distributions at large x/sub F/ show evidence for diffractive or resonance production.

In an experiment performed at the CERN PS using the HYperon BUbble Chamber (HYBUC), we have measured the asymmetry parameter αγ for the decay Σ+→pγ. The result is αγ = −0.53+0.38−0.36 For the branching ratio we find Γ(Σ + → p γ) Γ(Σ + → p π 0 ) = (2.11 ± 0.38) × 10 −3 .

The reaction ..pi../sup -/N..-->..K/sub S//sup 0/K/sub S//sup 0/..pi../sup -/N' at 200 GeV/c has been observed with a sensitivity of 450 +- 150 events/..mu..b. The K/sub S//sup 0/K/sub S//sup 0/..pi../sup -/ system exhibits substantial K/sup asterisk-/(890)K/sup 0/ production. Also produced are f/sup 0/(1270)..pi../sup -/, f'(1515)..pi../sup -/, and K/sup asterisk-/(1430)K/sup 0/ final states. These resonances occur predominantly at threshold. The diffractive K/sub S//sup 0/K/sub S//sup 0/..pi../sup -/ cross section is 3.4 +- 1.1 ..mu..b. An enhancement near the A/sub 3//sup -/(1680) is observed in the K/sub S//sup 0/K/sub S//sup 0/..pi../sup -/ invariant-mass distribution.

We have carried out an amplitude analysis of the K/sup 0//sub S/K/sup 0//sub S/ system produced in the reaction ..pi../sup -/p..-->..K/sup 0//sub S/K/sup 0//sub S/n at 23 GeV/c, based on about 15 000 events in the low-t region (Vertical Bart-t/sub min/Vertical Bar

We report on the final result of a precision measurement of the ${\ensuremath{\Sigma}}^{+}$ magnetic moment using the hyperon bubble chamber (HYBUC). HYBUC is a hydrogen bubble chamber with an 11.5-T superconducting magnet and was built by the Max-Planck-Institut f\"ur Physik und Astrophysik and Vanderbilt University for this experiment. A detailed description of the experiment, apparatus, and analysis is given. The final result is ${\ensuremath{\mu}}_{{\ensuremath{\Sigma}}^{+}}=(2.30\ifmmode\pm\else\textpm\fi{}0.14){\ensuremath{\mu}}_{N}$.

Bubble Chamber pictures show many undesired tracks and background in addition to the tracks of the desired significant event. Settles et al. have described a technique for optical tagging of an event by adding a darkfield photograph taken before significant bubble growth to a later brightfield photograph. We describe a system to cancel out all picture detail except for the wanted tracks by using a single vidicon tube as the storage device. In the first exposure, polarized light is imaged on the vidicon after passing through a Ronchi grating placed at a focal plane. Thus half of the target is exposed in a series of vertical stripes. The second exposure uses light polarized orthogonally to the first exposure and is deflected after passing through the Ronchi grating so as to expose the previously occluded stripes on the target. The target is then scanned orthogonally to the stripes; by subtracting the picture contained in one set of stripes from the contained in the other set, only the differences between the two images remains. A simulation was conducted using continuously presented background of one polarization and background plus tracks of the other polarization. The test showed that the added tracks were easily resolved, even though they were not readily discernible by visual inspection prior to subtraction.

An apparatus consisting of two magnetic spectrometers has been constructed at the CERN Proton Synchrotron (PS) in a missing-mass experiment to identify and select the beam particle and the outgoing one, and to measure their momenta. This paper gives details of the two spectrometers, which are comprised of multiwire proportional chambers, high resolution time-of-flight counters, and aerogel and water Cherenkov detectors.

The solenoid is a composite magnet with 15 NbTi outer coils and a Nb 3 Sn inner coil connected in series electrically. It has an inside diameter of 18.5 cm and a length of 59.1 cm. The magnet system has reached in tests fields up to 11.7 T, which is within 1% of the short sample limit of its conductors. The magnet showed little “training”. It has over 5000 h of operation at fields in excess of 11.0 T. Technical features of the system include: (a) mechanical design which emphasizes strength at the expense of having poor helium ventilation; (b) use of copper oxide coating for insulation; (c) use of twisted filaments in the NbTi composite portion of the solenoid; (d) interleaved high purity Al foils used in the high radial field regions of the Nb 3 Sn portion. Current densities vary between 5 700 and 16 000 A/cm 2 . The field has been mapped in detail and agrees with the theoretical field map to within about 2%.

We report on new measurements of the ${\ensuremath{\Sigma}}^{+}$ and ${\ensuremath{\Sigma}}^{\ensuremath{-}}$ lifetimes, the ${\ensuremath{\Sigma}}^{+}$ nonleptonic-decay branching ratio, and the ratio of the ${\ensuremath{\Sigma}}^{+}$ decay asymmetry parameters $\frac{{\ensuremath{\alpha}}_{+}}{{\ensuremath{\alpha}}_{0}}$. The final results obtained are ${\ensuremath{\tau}}^{+}=(0.798\ifmmode\pm\else\textpm\fi{}0.005)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}10}$ sec, ${\ensuremath{\tau}}^{\ensuremath{-}}=(1.480\ifmmode\pm\else\textpm\fi{}0.014)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}10}$ sec, $R=\frac{\ensuremath{\Gamma}({\ensuremath{\Sigma}}^{+}\ensuremath{\rightarrow}p{\ensuremath{\pi}}^{0})}{\ensuremath{\Gamma}({\ensuremath{\Sigma}}^{+}\ensuremath{\rightarrow}\mathrm{all})}=0.5172\ifmmode\pm\else\textpm\fi{}0.0036$, and $\frac{{\ensuremath{\alpha}}_{+}}{{\ensuremath{\alpha}}_{0}}=\ensuremath{-}0.073\ifmmode\pm\else\textpm\fi{}0.021$. These results together with the world average for ${\ensuremath{\alpha}}_{0}$ are used to perform a test of the $|\ensuremath{\Delta}I|=\frac{1}{2}$ rule.

The reactions π − d → K + + MM and K − d → π + + MM have been studied at 1.4 GeV / c to search for strange dibaryon states with quantum numbers Q = −1, and S = −1. No structures are found which could indicate the production of such states and upper limits for the cross sections are established.

From an exposure of the 30-inch deuterium filled bubble chamber to a 100 GeV/ c antiproton-enriched beam at FNAL, we have calculated the topological cross sections for antiproton-neutron interactions with three or more charged particles in the final state. A comparison of our data with pn data at the same momentum allows us to estimate the annihilation contribution to each multiplicity, and hence calculate the average value, and width, of the annihilation multiplicity distribution. Our results are consistent with those from p p data at 100 GeV/ c , but depart from the trend of lower-energy p p data.

The reaction K− + d → K+ + MM has been studied at 1.4 GeV/c, to search for Q = −1, S = −2 dibaryonic states, in the mass range ≈ 2.1–2.5 GeV/c2. No evidence for the presence of structures has been found and upper limits for the backward production differential cross section for narrow states are established.

Current-voltage characteristics are presented for pressure contacts between type-II superconductors and normal metals. The characteristics are studied as a function of temperature and magnetic field. A simple model of the phenomenon indicates that, under suitable conditions, a measure of the energy gap at the boundary can be obtained directly from the $I\ensuremath{-}V$ characteristics.

A sample of 52 $\ensuremath{\Sigma}p$ decays satisfying hydrogen-like production kinematics yields ${\ensuremath{\mu}}_{{\ensuremath{\Sigma}}^{+}}=+3.5\ifmmode\pm\else\textpm\fi{}1.5{\ensuremath{\mu}}_{N}$ and $\ensuremath{\alpha}\overline{P}=\ensuremath{-}0.69\ifmmode\pm\else\textpm\fi{}0.15$ relative to ${\stackrel{^}{P}}_{K}\ifmmode\times\else\texttimes\fi{}{\stackrel{^}{P}}_{\ensuremath{\Sigma}}$. The effect of all magnetic field components along the ${\ensuremath{\Sigma}}^{+}$ path has been included, as well as that of the c.m. decay angle on detection efficiency. The measurement of ${\ensuremath{\mu}}_{{\ensuremath{\Sigma}}^{+}}$ can be averaged with an earlier result to give ${\ensuremath{\mu}}_{{\ensuremath{\Sigma}}^{+}}=+3.2\ifmmode\pm\else\textpm\fi{}0.9{\ensuremath{\mu}}_{N}$, consistent with the prediction by SU(3).

The first photoproduced sigmas have been observed by placing nuclear emulsions within a few mm of a C${\mathrm{H}}_{2}$ target. One dozen in-flight decays (10 $\ensuremath{\Sigma}'\mathrm{s}$ and 2 ${\ensuremath{\Lambda}}^{0}'\mathrm{s}$ have been identified. The background which previously would have prevented useful exposures has been sharply reduced by applying a 160 KG field along the photon beam. The bulk of the electrons are held in small orbits while the heavier charged sigmas are relatively unaffected. Both of the sigma decay modes have been observed, as well as the charged mode for ${\ensuremath{\Lambda}}^{0}$ decay. The sign of the charged-pion sigma decays cannot be distinguished. The sigma proton decay can only come from the ${\ensuremath{\Sigma}}^{+}$ and this experiment provides the first measurement of the reaction, $\ensuremath{\gamma}+p\ensuremath{\rightarrow}{\ensuremath{\Sigma}}^{+}+{K}^{0}$. No event has been included with less than 10% difference in ionization between primary and secondary. All observed events had at least one track with ionization greater than 2\ifmmode\times\else\texttimes\fi{} minimum. If one corrects for the assumed loss of lighter events, the average cross section for photon energies between 1100 and 1200 MeV and for kaon c.m. angles between 30\ifmmode^\circ\else\textdegree\fi{} and 120\ifmmode^\circ\else\textdegree\fi{} (\ensuremath{\sim}60\ifmmode^\circ\else\textdegree\fi{} c.m.) in $\ensuremath{\gamma}+p\ensuremath{\rightarrow}{\ensuremath{\Sigma}}^{+}+{K}^{0}$ is (4\ifmmode\pm\else\textpm\fi{}2)\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}31}$ ${\mathrm{cm}}^{2}$/sr.

Isotopic spin and isotopic displacementU/2 are assigned to the leptons on the basis of the formulaq= U/2 + T3 and the assumption that the muon is an isosinglet and that the e-v is an isodoublet. We postulate a scheme that allows interactions involving fermions only if they can form a pair with aU of 0, ±1. Selection rules for weak, strong and electromagnetic interactions are given which are in agreement with known reactions. Reactions not yet investigated are listed which can test some of the proposed rules.

The photodisintegration of complex nuclei by gamma rays up to 1150 Mev has been studied by exposing nuclear emulsion to bremsstrahlung from the CalTech electron synchrotron and observing the "photostars" produced. Exposures were made at 16 different peak energies between 250 and 1150 Mev. Nearly 10 000 photostars were analyzed for star frequency, prong number, angular distribution, and (at 1143 Mev) the visible energy release per star. The bremsstrahlung yield of multiprong (\ensuremath{\ge}2 prong) stars increases abruptly as photons capable of producing pions are included. The cross section per photon, derived from the bremsstrahlung yield by the photon difference method, is essentially constant at 250 microbarns/nucleon at all energies above 300 Mev. A model for photostar production is given which involves photopion production followed by absorption or scattering of the pion and recoil nucleon. Experimental free-nucleon photopion cross sections are used, together with the Monte Carlo calculations of Metropolis et al., to determine the probability for star formation. Good agreement with both the shape and magnitude of the excitation curve is obtained if nuclear motion is included. Mean and maximum prong numbers for photostars are the same as for stars produced by pions or protons of equal available energy. The mean-free-paths in nuclear matter of pions and protons are short, so that photostar yields are a measure of the integrated total photomeson cross section. More than 95% of the multiprong stars made by 1-Bev bremsstrahlung are made by photons whose energies exceed the pion production threshold of 150 Mev. Most of the 1-prong events are produced by photons below 150 Mev, and the yield is consistent with giant resonance ($\ensuremath{\gamma}, p$) reactions plus "pseudodeuteron" photodisintegration, a process whose cross section rapidly decreases as the photon energy increases. Variation of mean prong number with energy and comparison with nuclear cascade calculations suggests that the excitation of the residual nucleus is nearly constant at 100 Mev over a wide range of incident photon energies. The visible energy release per photostar shows a linear dependence on prong number, and more than half of the photon energy is carried away by neutral particles.

The critical current of Nb/sub 3/Sn wires clad in Nb is measured at 4.2 deg K and at 0 to 130 kgauss. The effects of both longitudinal and transverse magnetic fields are studied. The magnetic field is pulsed, and current pulses of 30 to 150 mu sec are passed through the sample at the peak of the magnetic field pulses. The superconducting-normal transition time and the sample resistance are also measured. (T.F.H.)

Experiments were carried out to determine the spectral distribution of electron tracks produced in the emulsion by either photoelectric or Compton effect of X-rays from the plasma focus. The 600- mu -thick Ilford emulsions, stacked behind a 1.5 mm-thick lead absorber, were placed at a distance of 90 cm from the source on the axis of the electrode. The electron ranges were measured with Leitz scanning microscopes equipped with an 18 mu reticle grid.

In this paper preliminary results of an experiment, which is being run at the CERN Proton Synchrotron (PS) since May 1979, are reported.

Results are reported concerning the charged-particle multiplicity distribution obtained in an exposure of the high-resolution hydrogen bubble chamber LEBC to a beam of 800 GeV protons at the Fermilab MPS. This is the first time that such data have been available at this energy. The distribution of the number n ch of charged particles produced in inelastic interactions obeys KNO-scaling. The average multiplicity is 〈 n ch 〉 = 10.26±0.15. For n ch ⩾8 the data can be well fitted to a negative binomial. The difference between the overall experimental multiplicity distribution and that resulting from the latter fit is in agreement with the contribution expected from diffractive processes.

The interactions of 420—500 Me V/c K− in the 11T hydrogen bubble chamber HYBUC have been used to produce a sample of 120,000 σ± decays in flight1,2. We describe here how these decays were used to investigate the effects of longitudinal accelerations between 0.5 and 5.0 × 1015g on particle lifetimes. Any observed effect of acceleration on lifetime would indicate that the Lorentz transformation and/or the dynamics of particle decay is sensitive to acceleration. These data suggest that accelerations which change the Lorentz factor and which can return a relativistic elementary particle clock to rest do not cause any observable change in lifetime. This null result complements earlier measurements of the effects of transverse acceleration on muons13. Thus ensembles of elementary particles are ideal clocks which are invariant under intense accelerations.

Pulsed magnetic fields of ∼270 kG which are repeatable to