Ground state hyperfine structures of 43K and 44K measured by atomic beam magnetic resonance coupled with laser optical pumping

The ground state hyperfine structures of 43 K and 44K have been measured by an atomic beam magnetic resonance method in which the atoms are spin-polarized by laser optical pumping. The spectroscopic results are : Δv43( 2S1/2) = 192.648 4 (30) MHz and Δν44( 2S1/2) = - 946.718 (3) MHz. The sensitivity of our method is compared to the one achieved in classical ABMR apparatus

Protons in near earth orbit

The proton spectrum in the kinetic energy range 0.1 to 200 GeV was measured by the Alpha Magnetic Spectrometer (AMS) during space shuttle flight STS-91 at an altitude of 380 km. Above the geomagnetic cutoff the observed spectrum is parameterized by a power law. Below the geomagnetic cutoff a substantial second spectrum was observed concentrated at equatorial latitudes with a flux ~ 70 m^-2 sec^-1 sr^-1. Most of these second spectrum protons follow a complicated trajectory and originate from a restricted geographic region.Comment: 19 pages, Latex, 7 .eps figure

Search for antihelium in cosmic rays

The Alpha Magnetic Spectrometer (AMS) was flown on the space shuttle Discovery during flight STS-91 in a 51.7 degree orbit at altitudes between 320 and 390 km. A total of 2.86 * 10^6 helium nuclei were observed in the rigidity range 1 to 140 GV. No antihelium nuclei were detected at any rigidity. An upper limit on the flux ratio of antihelium to helium of < 1.1 * 10^-6 is obtained.Comment: 18 pages, Latex, 9 .eps figure

A Study of Cosmic Ray Secondaries Induced by the Mir Space Station Using AMS-01

The Alpha Magnetic Spectrometer (AMS-02) is a high energy particle physics experiment that will study cosmic rays in the $\sim 100 \mathrm{MeV}$ to $1 \mathrm{TeV}$ range and will be installed on the International Space Station (ISS) for at least 3 years. A first version of AMS-02, AMS-01, flew aboard the space shuttle \emph{Discovery} from June 2 to June 12, 1998, and collected $10^8$ cosmic ray triggers. Part of the \emph{Mir} space station was within the AMS-01 field of view during the four day \emph{Mir} docking phase of this flight. We have reconstructed an image of this part of the \emph{Mir} space station using secondary $\pi^-$ and $\mu^-$ emissions from primary cosmic rays interacting with \emph{Mir}. This is the first time this reconstruction was performed in AMS-01, and it is important for understanding potential backgrounds during the 3 year AMS-02 mission.Comment: To be submitted to NIM B Added material requested by referee. Minor stylistic and grammer change

Cosmic-ray positron fraction measurement from 1 to 30 GeV with AMS-01

A measurement of the cosmic ray positron fraction e+/(e+ + e-) in the energy range of 1-30 GeV is presented. The measurement is based on data taken by the AMS-01 experiment during its 10 day Space Shuttle flight in June 1998. A proton background suppression on the order of 10^6 is reached by identifying converted bremsstrahlung photons emitted from positrons

MEASUREMENT OF THE NUCLEAR gI FACTOR BY LASER OPTICAL PUMPING AND LARMOR PRECESSION IN A FAST ATOMIC BEAM

The extraction of the nuclear dipolar magnetic moment [MATH]n from the hyperfine structure constants requires the calculation of the electronic contribution and this limits the accuracy which moreover depends on the hyperfine anomaly. To overcome these difficulties, we present an original method of determining the nuclear Landé factor gI for diamagnetic atoms. This new technique is illustrated with two experiments using respectively the odd-A isotopes 135,137Ba (I = 3/2 - test experiment /1/) and the odd-A isotopes 213,225Ra (I = 1/2 - this experiment was carried out at C.E.R.N. on line with the ISOLDE mass separator). The method, based on the fast atomic beam laser spectroscopy technique, consists of detecting the in-flight Larmor precession of the nuclear magnetic moment in a static field, via the fluorescence induced by a resonant laser light

Electronic shells and supershells in trivalent metal clusters

No abstract availabl

Optical resonance detection by field ionization of Rydberg state in colinear laser spectroscopy

New efficient non-optical detection methods of optical resonances in colinear laser spectroscopy are described. A first method uses the field ionization of a Rydberg state populated by means of two lasers : one is single frequency and interacts colinearly with the fast atomic beam, the other one is multimode and interacts perpendicularly. By detecting, at resonance, the produced ions instead of the fluorescence photons, an overall efficiency of 1.1 x 10 -5 has been obtained, which is comparable to the usual sensitivity limit reached by the laser induced fluorescence method. A second similar experiment uses two single mode dye lasers both interacting colinearly with the fast atomic beam. Compared to the first technique an increase of the sensitivity by two orders of magnitude has been obtained (corresponding to an efficiency of 1.2 x 10- 3). Application to the study of on line produced short-lived isotopes is discussed.Deux nouvelles méthodes efficaces, et non optiques, de détection de résonance optique en spectroscopie colinéaire sont décrites. La première méthode utilise l'ionisation par champ d'un état de Rydberg peuplé à l'aide de deux lasers : le premier est monomode et interagit colinéairement avec le jet d'atomes rapides et le second est multimode et interagit perpendiculairement. En détectant, à la résonance, les ions produits à la place des photons de fluorescence, on obtient une efficacité de 1,1 x 10-5 qui est comparable à la limite de sensibilité habituellement atteinte par la méthode de fluorescence induite par laser. Une deuxième expérience similaire utilise deux lasers à colorant monomodes tous deux interagissant colinéairement avec le faisceau d'atomes rapides. Par comparaison avec la première méthode, on obtient un accroissement de la sensibilité de deux ordres de grandeur (correspondant à une efficacité de 1,2 x 10-3). L'application de ces méthodes à l'étude d'isotopes de courte durée de vie, produits en ligne, est examinée

PRODUCTION OF METAL CLUSTER BEAMS BY USER VAPORIZATION

Using laser vaporization technique and standard Time-Of-Flight (TOF) spectrometric methods, Ionization Potentials (IP) of aluminum and iron clusters have been measured in extensive size ranges. These results are compared with recently published experimental works and analyzed in the self-consistent Spherical Jellium Background Model framework (SJBM)