Balloon-borne Detector Research Articles

Atmospheric Response for MeV γ Rays Observed with Balloon-borne Detectors

The atmospheric response for MeV γ rays (∼0.1–10 MeV) can be characterized in terms of two observed components. The first component is due to photons that reach the detector without scattering. The second component is due to photons that reach the detector after scattering one or more times. While the former can be determined in a straightforward manner, the latter is much more complex to quantify, as it requires tracking the transport of all source photons that are incident on Earth’s atmosphere. The scattered component can cause a significant energy-dependent distortion in the measured spectrum, which is important to account for when making balloon-borne observations. In this work, we simulate the full response for γ-ray transport in the atmosphere. We find that the scattered component becomes increasingly more significant toward lower energies, and at 0.1 MeV, it may increase the measured flux by as much as a factor of ∼2–4, depending on the photon index and off-axis angle of the source. This is particularly important for diffuse sources, whereas the effect from scattering can be significantly reduced for point sources observed with an imaging telescope.

The antinucleus annihilation reconstruction algorithm of the GAPS experiment

The General AntiParticle Spectrometer (GAPS) is an Antarctic balloon-borne detector designed to measure low-energy cosmic antinuclei (<0.25GeV/n), with a specific focus on antideuterons, as a distinctive signal from dark matter annihilation or decay in the Galactic halo. The instrument consists of a tracker, made up of ten planes of lithium-drifted Silicon Si(Li) detectors, surrounded by a plastic scintillator Time-of-Flight system. GAPS uses a novel particle identification method based on exotic atom capture and decay with the emission of pions, protons, and atomic X-rays from a common annihilation vertex.An important ingredient for the antinuclei identification is the reconstruction of the “annihilation star” topology. A custom antinucleus annihilation reconstruction algorithm, called the “star-finding” algorithm, was developed to reconstruct the annihilation star fully, determining the annihilation vertex position and reconstructing the tracks of the primary and secondary charged particles. The reconstruction algorithm and its performances were studied on simulated data obtained with the Geant4-based GAPS simulation software, which fully reproduced the detector geometry. This custom algorithm was found to have better performance in the vertex resolution and reconstruction efficiency compared with a standard Hough-3D algorithm.

The SPHERE-2 detector for observation of extensive air showers in 1 PeV – 1 EeV energy range

The SPHERE-2 balloon-borne detector designed for extensive air shower (EAS) observations using EAS optical Vavilov-Cherenkov radiation (“Cherenkov light”), reflected from the snow-covered surface of Lake Baikal is described. We briefly discuss the concept behind the reflected Cherenkov light method, characterize the conditions at the experimental site and overview the construction of the tethered balloon used to lift the SPHERE-2 telescope above the surface. This paper is mainly dedicated to a detailed technical description of the detector, including its optical system, sensitive elements, electronics, and data acquisition system (DAQ). The results of some laboratory and field tests of the optical system are presented.

Cosmic ray catcher will probe supernovae from new perch.

Balloon-borne detector moves to space to trap rare, high-energy particles that carry clues to their origin.

The ExaVolt Antenna: Concept and Development Updates

A flux of ultrahigh energy neutrinos is expected both directly from sources and from interactions between ultrahigh energy cosmic rays and the cosmic microwave background. Using the cost-effective radio Cherenkov technique to search for these neutrinos, the ExaVolt Antenna (EVA) is a mission concept that aims to build on the capabilities of earlier radio-based balloon-borne neutrino detectors and increase the sensitivity to lower energies and fluxes. The novel EVA design exploits the surface of the balloon to provide a focusing reflector that aims to provide a signal gain of ~ 30 dBi (compared to 10 dBi on ANITA). This increase in gain when combined with a large instantaneous viewing angle will yield a 10-fold increase in sensitivity and will allow this balloon-borne experiment to probe the expected low neutrino fluxes even at energies greater than 10 19 eV. This contribution will present an overview of the mission concept, recent technology developments, and the results of a hang test of a 1:20-scale model which demonstrates the effectiveness of the design.

Detection of lower tropospheric responses to solar energetic particles at midlatitudes.

Solar energetic particles (SEPs) occasionally contribute additional atmospheric ionization beyond that arising from the usual galactic cosmic ray background. During an SEP event associated with a solar flare on April 11, 2013, the vertical ionization rate profile obtained using a balloon-borne detector showed enhanced ionization with a 26% increase at 20km, over Reading, United Kingdom. Fluctuations in atmospheric electrical parameters were also detected at the surface, beneath the balloon's trajectory. As no coincident changes in geomagnetism occurred, the electrical fluctuations are very likely to be associated with increased ionization, as observed by the balloon measurements. The lack of response of surface neutron monitors during this event indicates that energetic particles that are not detected at the surface by neutron monitors can nevertheless enter and influence the atmosphere's weather-generating regions.

Direct measurements of cosmic rays using balloon borne experiments

Direct measurements of cosmic rays with balloon-borne detectors are used for understanding cosmic ray origin, acceleration and propagation, as well as exploring the supernova acceleration limit and searching for exotic sources such as dark matter. The energy reach of direct measurements is currently limited to ∼1015eV by the detector size and exposure time, but incident particles are identified element-by-element with excellent charge resolution. A challenge of balloon-borne experiments is that the detectors must be large enough to collect adequate statistics, yet stay within the weight limit available for balloon flight. Innovative approaches now promise high quality measurements over an energy range that was not previously possible. Recent results and their implications are reviewed. The outlook of existing and future experiments is also discussed.

Cosmic ray primary composition in the energy range 10–1000 TeV obtained by passive balloon-borne detector: Reanalysis of the RUNJOB experiment

We search for a consistent view on the RUNJOB experiment and present an alternative analysis based on explicitly reported and published numerical data. Here we show that there is more than one interpretation to the reported observational data. It is demonstrated that, contrary to the wide-spread opinion, the RUNJOB data are not inconsistent with an increase of the average mass near the knee region of the cosmic ray spectrum. Considering very low statistics and systematic uncertainties, especially in the high energy region, we suggest that peculiarities of the methodical origin were the most likely source of those RUNJOB conclusions which contradicted previous observations reported by other groups.

Temperature and pressure conditions for the appropriate performance of charge and mass resolutions in balloon-borne CR-39 track detector for the heavy cosmic rays

We experimentally determined the suitable conditions of temperature and air pressure for measuring charge and mass compositions of heavy cosmic rays using CR-39 track detectors during long-duration, high-altitude balloon flights. The experiments were carried out utilizing Fe ion beams from Heavy Ion Medical Accelerator (HIMAC). Changes in the track registration sensitivity with temperature were studied at temperatures between 213 and 293 K. The charge and mass shifts around Fe ions are possibly 0.11 cu (charge unit) and 0.47 amu (atomic mass unit) at the temperature deviation between 227 and 243 K at balloon altitude. Decrease in track registration sensitivity as air pressure decreases has been observed between 13 Pa and 27 kPa. The charge and mass shifts around Fe ions are inferred to be 0.02 cu and 0.09 amu, respectively, when pressure varies between 20 and 27 kPa. During balloon flight, air pressure drops below this; therefore, care must be taken to keep the temperature and air pressure of CR-39 detectors within acceptable limits.

Antarctic balloon-borne detector of high-energy cosmic rays (SPHERE project)

The experiment SPHERE is based on a A.E. Chudakov's suggestion to use a new method for investigations of the energy spectrum of ultrahigh-energy primary cosmic rays. A small device lifted up off a snowed surface of the Earth detects Cherenkov light of an extensive air shower that is reflected from the surface. A contemporary status of the experiment SPHERE, a description of the method, the first measurements of the background night starlight in the region of the Russian Antarctic station Novolazarevskaya are presented. A relatively simple detector SPHERE-2 including a spherical mirror of the diameter 1.5 m and a 100-pixel retina is developed for Antarctic balloon-borne measurements of the cosmic ray spectrum. A long-time winter flight makes it possible to measure the spectrum above 10 20 eV . A comparison with satellite and ISS projects of the nearest future shows that efficiency of this detector is sufficiently high.

The Energy Spectra and Relative Abundances of Electrons and Positrons in the Galactic Cosmic Radiation

Observations of cosmic-ray electrons and positrons have been made with a new balloon-borne detector, HEAT (the High-Energy Antimatter Telescope), first flown in 1994 May from Fort Sumner, NM. We describe the instrumental approach and the data analysis procedures, and we present results from this flight. The measurement has provided a new determination of the individual energy spectra of electrons and positrons from 5 GeV to about 50 GeV, and of the combined all-electron intensity (e+ + e-) up to about 100 GeV. The single power-law spectral indices for electrons and positrons are alpha = 3.09 +/- 0.08 and 3.3 +/- 0.2, respectively. We find that a contribution from primary sources to the positron intensity in this energy region, if it exists, must be quite small.

Hard X‐Ray Emission from the Galactic Ridge

Hard X-ray and γ-ray emissions from the Galactic ridge were studied with the large area proportional counter (LAC) on the Ginga satellite and a balloon-borne detector Welcome-1. In the scanning observations with the LAC, diffuse hard X-rays were detected along the Galactic plane between l = -20° and l = 40°. The measured spectrum shows that a hard component exists in the Galactic ridge emission above 10 keV, in addition to the hot plasma component. The estimated luminosity of the Galactic ridge emission is around 2 × 1038 ergs s-1 in the 3-16 keV band. Welcome-1 observed the γ-ray ridge emission at around l ~ 345° between 50 and 600 keV. These two results and a recent COMPTEL study suggest that the spectrum of the diffuse Galactic ridge emission extends over the keV-MeV range. From the observed spectral slope, bremsstrahlung by electrons is shown to be the dominant emission mechanism. This implies that low-energy electrons must be supplied continuously to sustain emission in the hard X-ray band. We propose a scenario in which the thermal electrons in the hot plasma responsible for the strong Fe K X-ray emission are shock-accelerated continuously in supernova remnants (SNRs), producing the observed hard X-ray and γ-ray emissions from the Galactic ridge.

Low power high resolution TDC with fast data conversion for balloon-borne experiments

A new low power CAMAC TDC module with a resolution of 26 psec and fast data conversion for time-of-flight measurement on a balloon-borne particle detector is described. The module incorporates sixteen TAC channels in single CAMAC width, and the total power consumption is 0.8 W/ch. The temperature coefficient of the conversion gain is typically 20 ppm//spl deg/C so that an influence of a wide variation of the ambient temperature during the flight could be reduced. Each channel has a hit register scanned by a sequencer and digitizations of non-stopped channels are skipped, thus minimizing the conversion time and the data volume.

Experiments searching for nonbaryonic dark matter

It is increasingly likely that the universe has critical density, the only time-stable value, and that therefore at least 90% of its mass is in a nonbaryonic form outside the Standard Model of particle physics. Probably ∼ 70% of this mass is cold dark matter and the rest hot, in the form of neutrinos with total mass summed over all active species of ∼ 5 eV. If the solar ν e and atmospheric ν μ deficits also require neutrino mass, then there are only two viable patterns for those masses: (1) the ν e , ν μ , and ν τ are all ∼ 2 eV, or (2) the ν e and a sterile neutrino, ν e can be light, and the ν μ and ν τ are ∼ 3 eV. Terrestrial experiments are needed to determine the neutrino masses, and there are already hints of effects from the LSND neutrino oscillation experiment and possibly from neutrinoless double beta decay. Information on cold dark matter can be obtained from accelerator experiments, searches for dark matter annihilation products, and direct detection of the dark matter particles. This third approach has already eliminated a span of 13 orders of magnitude in mass for Dirac particles and 20 orders of magnitude in their interaction cross section. New direct detection experiments include a search for axions through their conversion to microwave photons in a magnetic field and numerous searches using a variety of scintillators and new types of cryogenic devices to detect nuclei struck by dark matter particles. The latter searches and those attempting to find annihilation products in balloon-borne and large underground detectors now especially seek the supersymmetric neutralino.

An X-ray observation in the atmosphere during the August 7, 1972 solar flare

An observation carried out with a balloon-borne detector of an additional flux of secondary X-rays (E ≃ 30 keV) at large depths in the atmosphere is described. This excess is attributed to the emission of very hard X-rays during the solar flare of August 7, 1972. The propagation in the atmosphere of the secondary photons resulting from their electromagnetic interactions in the air is computed by utilizing the Monte Carlo method. The computations agree with the observed flux when a very hard solar X-ray spectrum is assumed.

High-energy electron and gamma-ray fluxes in the Brazilian Magnetic-Anomaly Region

Fluxes of electrons and gamma-rays with energies around a few tens of MeV were measured with a balloon-borne detector in November, 1991, in Bauru, (Brazil). The altitude dependences of fluxes and the indices of the differential energy spectra obtained at rigidity 12 GV (Bauru) are compared with results obtained with the same detector at rigidity 3.5 GV in the Volga region (Volsk), Russia.

Flight performance of EXAM — a balloon-borne detector to search for extragalactic antimatter

We describe the performance of the EXAM detector during its five hour balloon flight in 1988. EXAM is an experiment designed to search for cosmic rays of extragalactic origin which are made of antimatter. The EXAM technique to identify antinuclei is unique, being based on higher order corrections to electronic stopping power of charged particles, and on the response characteristics of CR-39 track-etch detectors, plastic scintillators, and Cherenkov radiators. Included in the present paper are the completed analysis of the electronic detectors, and preliminary results of the analysis of the track-etch detectors, including a demonstration of our ability to match particles identified with the drift tube tracking elements during the flight with their tracks found in the passive CR-39 detectors. When the CR-39 analysis is complete, we will have approximately 10 000 events for which antimatter analysis can be made.

Low power ADC with fast zero suppression for balloon-borne experiment

A low power CAMAC analog-to-digital converter (ADC) module with fast zero suppression is described. The module is developed to improve data acquisition rate for a balloon-borne detector. The module is of a single CAMAC width and includes sixteen charge-to-voltage converter (QVC) channels. Each channel has its own A/D converter. The QVC outputs are digitized simultaneously. The A/D converter continues digitization for 15 mu s at longest. A microprogrammed sequencer, which is installed in the module, scans the channels, comparing the outputs of the A/D converters with prescribed thresholds. The outputs are stored together with channel numbers into data memory when the outputs are greater than the thresholds. The zero suppression completes in 3 mu s, and zero-suppressed data become ready within 18 mu s. The operation of the QVC circuit is repeatedly simulated on a workstation in order that the temperature dependence of the QVC circuit can be reduced without sacrificing performance. >

A limit on the Co-57 gamma-ray flux from SN 1987A

view Abstract Citations (17) References (19) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS A Limit on the 57Co Gamma-Ray Flux from SN 1987A Gunji, S. ; Kamae, T. ; Miyazaki, S. ; Sekimoto, Y. ; Takahashi, T. ; Tamura, T. ; Tanaka, M. ; Yamaoka, N. ; Yamagami, T. ; Nomachi, M. ; Murakami, H. ; Braga, J. ; Neri, J. A. Abstract We studied the γ-ray flux from SN 1987A with a balloon-borne detector in Brazil on 1990 November 29. By comparing on- and off-source data, we obtained limits to the total γ-ray flux due to ^57^Co decays and presumed pulsar activity. If the pulsar contribution is neglected, an upper limit (90% confidence limit) is set to the total ^57^Co contribution above 60 keV at 2.7 x 10^-4^ cm^-2^ s^-1^ where the 122 keV line contribution is 1.0 x 10^-4^ cm^-2^ s^-1^. The corresponding limit on the abundance ratio of ^57^Co and ^56^Co is 3.4 times that of the Sun. The present upper limit implies that the reported leveling off in the light curve of SN 1987A is primarily due to the pulsar activity. If the pulsar is Crab-like (photon index - 2.2), the light curve requires an energy outflow greater than 0.95 x 10^37^ ergs s^-1^ (above 1 keV) now being supplied to SN 1987A by its presumed pulsar. Publication: The Astrophysical Journal Pub Date: October 1992 DOI: 10.1086/186550 Bibcode: 1992ApJ...397L..83G Keywords: Abundance; Cobalt Isotopes; Gamma Rays; Nuclear Reactions; Supernova 1987a; Balloon-Borne Instruments; Light Curve; Astrophysics full text sources ADS | data products NED (2) SIMBAD (1)

Estimation of chemical abundance of primary cosmic-ray nuclei over Alice Springs using balloon-borne passive detectors

A stack consisting of CR-39 (HCB 0.5%), nuclear emulsions and X-ray films was exposed to primary cosmic rays by a balloon lauched from Alice Springs in 1983 and was flown for 32 hours at an atmospheric depth 9.8 g cm−2 air. The recovered plastic plates were etched in 7.5 N NaOH solution at 80°C for 96 hours. The major and minor axes of the elliptic etch pits were analysed. About 1112 elliptic etch pits were scanned. The measured integral flux of very heavy (VH) and Fe nuclei above 3.5 GeV/n are in approximate aggreement with the earlier survey of Dokeet al., but yield a flatter energy spectrum when compared to the recent high-energy extrapolated spectrum of Zatsepinet al. The charges of the detected heavy nuclei were also confirmed from delta-ray counting of heavily ionized tracks in nuclear emulsions. The energy of the incident heavy nuclei has been measured from the distribution of opening angles of alpha fragments initiated by heavy nuclei in nuclear emulsions.