Photoionization of ultracold and Bose-Einstein condensed Rb atoms

Photoionization of a cold atomic sample offers intriguing possibilities to observe collective effects at extremely low temperatures. Irradiation of a rubidium condensate and of cold rubidium atoms within a magneto-optical trap with laser pulses ionizing through 1-photon and 2-photon absorption processes has been performed. Losses and modifications in the density profile of the remaining trapped cold cloud or the remaining condensate sample have been examined as function of the ionizing laser parameters. Ionization cross-sections were measured for atoms in a MOT, while in magnetic traps losses larger than those expected for ionization process were measured.Comment: 9 pages, 7 figure

Atomic density and temperature distributions in magneto-optical traps

A theoretical investigation into density, pressure, and temperature distributions in magneto-optical traps is presented. After a brief overview of the forces that arise from reradiation and absorption, a condition that the absorptive force be conservative is used to show that, if the temperature is uniform throughout the trap, any. density solutions to the force equations will not be physical. Further, consistent density solutions are unlikely to exist at all. In contrast, with a varying temperature reasonable solutions are demonstrated, with some restrictions. Doppler forces involved in ring-shaped trap structures are used to calculate orbit radii in racetrack geometry traps, and corrections to the present discrepancy between theoretical and experimental studies are discussed in the context of reradiation and diffusion

Test of candidate light distributors for the muon (g−-2) laser calibration system

The new muon (g-2) experiment E989 at Fermilab will be equipped with a laser calibration system for all the 1296 channels of the calorimeters. An integrating sphere and an alternative system based on an engineered diffuser have been considered as possible light distributors for the experiment. We present here a detailed comparison of the two based on temporal response, spatial uniformity, transmittance and time stability.Comment: accepted to Nucl.Instrum.Meth.

A continuous source of translationally cold dipolar molecules

The Stark interaction of polar molecules with an inhomogeneous electric field is exploited to select slow molecules from a room-temperature reservoir and guide them into an ultrahigh vacuum chamber. A linear electrostatic quadrupole with a curved section selects molecules with small transverse and longitudinal velocities. The source is tested with formaldehyde (H2CO) and deuterated ammonia (ND3). With H2CO a continuous flux is measured of approximately 10^9/s and a longitudinal temperature of a few K. The data are compared with the result of a Monte Carlo simulation.Comment: 4 pages, 4 figures v2: small changes in the abstract, text and references. Figures 1 & 2 regenerated to prevent errors in the pd

The silicon microstrip detectors of the PAMELA experiment: simulation and test results

Abstract The PAMELA detector will fly at the beginning of 2004 on board the Russian satellite Resurs–DK for a 3-year mission designed to study mainly antiparticles in cosmic rays. The core of the apparatus is a magnetic spectrometer in which silicon microstrip detectors are employed. A dedicated simulation study, tuned on beam test data, is presented: it allows to determine the best position finding algorithm for different incidence angles

The magnetic spectrometer of the PAMELA satellite experiment

In this paper, we describe in detail the design and the construction of the magnetic spectrometer of the PAMELA experiment, that will be launched during 2003 to do a precise measurement of the energy spectra of the antimatter components in cosmic rays. This paper will mainly focus on the detailed description of the tracking system and on the solutions adopted to deal with the technical challenges that are required to build a very precise detector to be used in the hostile space environment

The PAMELA silicon tracker

Abstract The silicon tracker of the PAMELA apparatus has been assembled and it is ready to fly on-board the Russian satellite Resurs DK for a 3-year mission. The experiment will study, mainly, spectra of particles and antiparticles in cosmic rays. The magnetic spectrometer's primary goal is to precisely measure momenta of charged particles, whose trajectories have been bent by a permanent magnet. The detector is composed of 6 planes of double-sided silicon microstrip detectors, inserted between adjacent modules of a permanent magnet which produces an almost uniform magnetic field inside a rectangular cavity that particles cross. The spatial resolution of the detectors is about 3 μm for the bending coordinate. The development of such detectors required a complex manufacturing procedure in order to preserve the physical performance in a device suitable for a space mission. In the construction phase data originating from both beam tests and simulation helped to check the detector's characteristics and to optimize the achievable spatial resolution. The development and the final assembling of these detectors are described in this paper

A powerful tracking detector for cosmic rays: the magnetic spectrometer of the PAMELA satellite experiment

Abstract The WiZaxd-PAMELA detector will be ready within some months to be installed on board of the Russian satellite Resurs-DK1. The satellite will follow, for at least 3 years, a quasi polar orbit with an inclination of 70.4° with respect to the equatorial plane. The experiment will allow the measurement of the antiproton and positron spectra within a wide momentum range and the search for light anti-nuclei in cosmic rays. The detector subsystems have been tested and the final assembly phase is in progress. In this paper we describe the structure of the PAMELA magnetic spectrometer, its current status and some precautions taken to satisfy the requirements of the mission