A large area, high charge resolution, scintillation counter telescope for cosmic ray studies

The cosmic-ray mu-meson intensities at three different altitudes at the equator were measured as a function of zenith and azimuth angles by means of a portable scintillation counter telescope of semi-opening angles 23°. The data were analyzed to assess the effects of differences in pi- and mu-meson decay rates on the intensity of the penetrating ionizing component at different zenith angles. It was found that the changes of intensity as a function of zenith angles could be attributed almost entirely to differences in atmospheric absorption, provided that at all zenith angles the threshold rigidities were the same. Hence the intensities measured at different zenith angles in the east–west plane at the equator could be corrected to remove the atmospheric effects and the corrected data used for determining the response of meson detectors at sea level to particles of rigidity up to 25 GV. The response curve thus obtained is presented and compared with that obtained from sea-level latitude surveys by means of ionization chambers.

Download Full-text

Cosmic-ray proton and helium spectra and solar modulation effects in the new solar cycle measured with a four-element counter telescope

Canadian Journal of Physics ◽

10.1139/p68-374 ◽

1968 ◽

Vol 46 (10) ◽

pp. S883-S886 ◽

Cited By ~ 4

Author(s):

J. F. Ormes ◽

W. R. Webber

Keyword(s):

Scintillation Counter ◽

Pulse Height ◽

Cosmic Ray ◽

Geometrical Factor ◽

Solar Modulation ◽

Primary Proton ◽

Before And After ◽

Order Of Magnitude ◽

Helium Spectra ◽

Counter Telescope

In the summers of 1965 and 1966 we have continued our studies begun in 1963 on the primary proton and helium spectra and the effects of solar modulation. Data are available from four additional balloon flights at Fort Churchill using the earlier version of the Cerenkov-scintillation counter telescope (Ormes and Webber 1966), and a new four-element double-scintillation (dE/dx), Cerenkov-scintillation + range telescope. This latest telescope employs pulse-height analysis on both dE/dx counters and the Cerenkov-scintillation counter. Various consistency requirements may be set between pulse heights. These serve to reduce background effects by an order of magnitude over the previous system. The geometrical factor of the telescope is 55.4 sr cm2. The results reported here will cover the proton and helium spectra from 100 MeV/nucleon to 2 BeV/nucleon and their time variation. They will show that the fractional changes in the differential proton spectra can be represented by (rigidity)−1 both before and after the sunspot minimum and that there is no evidence for any hysteresis effects between protons of 100 MeV to 2 BeV and energies to which neutron monitors respond.

Download Full-text

Cosmic ray isotope and charge resolution using large area scintillation-cherenkov-total energy telescopes

Nuclear Instruments and Methods ◽

10.1016/0029-554x(72)90782-3 ◽

1972 ◽

Vol 99 (2) ◽

pp. 237-250 ◽

Cited By ~ 9

Author(s):

W.R. Webber ◽

J. Kish

Keyword(s):

Total Energy ◽

Cosmic Ray ◽

Large Area ◽

Charge Resolution

Download Full-text

Diffuse γ-ray emission toward the massive star-forming region, W40

Astronomy and Astrophysics ◽

10.1051/0004-6361/202037580 ◽

2020 ◽

Vol 639 ◽

pp. A80

Author(s):

Xiao-Na Sun ◽

Rui-Zhi Yang ◽

Yun-Feng Liang ◽

Fang-Kun Peng ◽

Hai-Ming Zhang ◽

...

Keyword(s):

Cosmic Ray ◽

High Energy ◽

Young Star ◽

Gas Content ◽

Large Area ◽

Stellar Cluster ◽

Production Region ◽

Star Forming ◽

Photon Index ◽

Young Star Clusters

We report the detection of high-energy γ-ray signal towards the young star-forming region, W40. Using 10-yr Pass 8 data from the Fermi Large Area Telescope (Fermi-LAT), we extracted an extended γ-ray excess region with a significance of ~18σ. The radiation has a spectrum with a photon index of 2.49 ± 0.01. The spatial correlation with the ionized gas content favors the hadronic origin of the γ-ray emission. The total cosmic-ray (CR) proton energy in the γ-ray production region is estimated to be the order of 1047 erg. However, this could be a small fraction of the total energy released in cosmic rays (CRs) by local accelerators, presumably by massive stars, over the lifetime of the system. If so, W40, together with earlier detections of γ-rays from Cygnus cocoon, Westerlund 1, Westerlund 2, NGC 3603, and 30 Dor C, supports the hypothesis that young star clusters are effective CR factories. The unique aspect of this result is that the γ-ray emission is detected, for the first time, from a stellar cluster itself, rather than from the surrounding “cocoons”.

Download Full-text

A possible radio signal of annihilating dark matter in the Abell 4038 cluster

Monthly Notices of the Royal Astronomical Society Letters ◽

10.1093/mnrasl/slz185 ◽

2019 ◽

Vol 495 (1) ◽

pp. L124-L128 ◽

Cited By ~ 2

Author(s):

Man Ho Chan ◽

Chak Man Lee

Keyword(s):

Dark Matter ◽

Cross Section ◽

Radio Signal ◽

Dark Matter Particle ◽

Cosmic Ray ◽

Annihilation Cross Section ◽

Radio Continuum ◽

Test Statistic ◽

Large Area ◽

Dark Matter Annihilation

ABSTRACT In the past decade, some telescopes [e.g. Fermi-Large Area Telescope (LAT), Alpha Magnetic Spectrometer(AMS), and Dark Matter Particle Explorer(DAMPE)] were launched to detect the signals of annihilating dark matter in our Galaxy. Although some excess of gamma-rays, antiprotons, and electrons/positrons have been reported and claimed as dark matter signals, the uncertainties of Galactic pulsars’ contributions are still too large to confirm the claims. In this Letter, we report a possible radio signal of annihilating dark matter manifested in the archival radio continuum spectral data of the Abell 4038 cluster. By assuming the thermal annihilation cross-section and comparing the dark matter annihilation model with the null hypothesis (cosmic ray emission without dark matter annihilation), we get very large test statistic values >45 for four popular annihilation channels, which correspond to more than 6.5σ statistical preference. This provides a very strong evidence for the existence of annihilating dark matter. In particular, our results also support the recent claims of dark matter mass m ≈ 30–50 GeV annihilating via the bb̄ quark channel with the thermal annihilation cross-section.

Download Full-text