994 research outputs found
Radiation environment along the INTEGRAL orbit measured with the IREM monitor
The INTEGRAL Radiation Environment Monitor (IREM) is a payload supporting
instrument on board the INTEGRAL satellite. The monitor continually measures
electron and proton fluxes along the orbit and provides this information to the
spacecraft on board data handler. The mission alert system broadcasts it to the
payload instruments enabling them to react accordingly to the current radiation
level. Additionally, the IREM conducts its autonomous research mapping the
Earth radiation environment for the space weather program. Its scientific data
are available for further analysis almost without delay.Comment: 5 pages, 7 figures, accepted for publication in A+A letter
Optimization of the final settings for the Space-borne Hard X-ray Compton Polarimeter POLAR
POLAR is a compact wide field space-borne detector dedicated for precise
measurements of the linear polarization of hard X-rays emitted by transient
sources in the energy range from 50 keV to 500 keV. It consists of 1600 plastic
scintillator bars grouped in 25 detector modules that are used as gamma-ray
detection material. Its energy range sensitivity is optimized for detection of
the prompt emission photons from the gamma-ray bursts. Measurements of the GRB
polarization provide unique information on emission mechanisms as well as on
composition and structure of the GRB jets. The POLAR instrument was developed
by international collaboration of Switzerland, China and Poland. It was
launched in space on-board the China Space Laboratory TG-2 on September 15th,
2016. Based on the ground calibration data, several high voltage and threshold
settings were calculated and verified in order to obtain various energy ranges
and optimized signal to background conditions for different measurement
purposes. In this paper we present optimization procedure details and current
test results.Comment: For 2017 ICRC conferenc
Radiocarbon chronology of the mammoth site at Niederweningen, Switzerland: results from dating bones, teeth, wood, and peat
Multiple Complications from a Finger Fracture in a Basketball Player
Minor finger and hand problems resulting from NCAA Division-1 Basketball competition are fairly common. True injuriesâ those requiring removal from participationâ are rare, as suggested by injury surveillance and epidemiological data. The objective of this study is to present the case of multiple complications resulting from an original finger dislocation and fracture. Improper fracture healing led to tendon imbalances, causing finger angulation. The extended period of time the finger was deformed further resulted in osteoarthritis (progressive wearing down of the cartilage and bones that comprise a joint). Severe complications stemming from the original injury occur infrequently in the general population and are virtually unheard of in the athletic population. Seemingly routine or inconsequential finger injuries may produce serious, permanent, and uncorrectable damage. Sports medicine practitioners should be familiar with the effects of injury on surrounding small and large tissue structures to provide optimal intervention and patient understanding. This knowledge will increase treatment compliance, preventing severe complications or permanent dysfunction
Radiocarbon dating and its applications in Quaternary studies
Dieser Beitrag gibt einen Ăberblick ĂŒber die Herkunft von Radiokohlenstoff, den globalen Kohlenstoffkreislauf, anthropogene EinflĂŒsse auf das atmosphĂ€rische 14C und die Grundlagen der Radiokohlenstoffmethode. Probenaufbereitung und das Messen der 14C Konzentration sind wichtige Aspekte im Zusammenhang mit der Radiokohlenstoffdatierung. GegenwĂ€rtige Fortschritte in der Probenaufbereitung erlauben ein besseres Verstehen lang bekannter Probleme (z.B. die Kontamination von Knochen) und haben zu verbesserten Chronologien gefĂŒhrt. In diesem Ăberblick werden verschiedene Aufbereitungstechniken fĂŒr typische Probengattungen beschrieben. Der letzte Schritt beim Erstellen einer Chronologie ist die Kalibration der Radiokohlenstoffalter. Die gegenwĂ€rtige auf Baumringzeitreihen basierende Kalibrationskurve wird stetig ĂŒber das HolozĂ€n und SpĂ€tglazial hinaus erweitert. Eine zuverlĂ€ssige Kalibrationkurve fuÌr die letzten 50.000â55.000 Jahre ist von herausragender Bedeutung sowohl fĂŒr die ArchĂ€ologie als auch die Geowissenschaften. In den letzten Jahren haben zahlreiche Studien an der Erweiterung der Radiokohlenstoff-Kalibrationskurve (INTCAL working group) und an der Rekonstruktion des PalĂ€o-Reservoireffekts in marinen Archiven gearbeitet.researc
Gamma-Ray Burst Polarization: Limits from RHESSI Measurements
Using the RHESSI satellite as a Compton polarimeter, a recent study claimed
that the prompt emission of GRB021206 was almost fully linearly polarized. This
was challenged by a subsequent reanalysis. We present an novel approach,
applying our method to the same data. We identify Compton scattering candidates
by carefully filtering events in energy, time, and scattering geometry. Our
polarization search is based on time dependent scattering rates in
perpendicular directions, thus optimally excluding systematic errors. We
perform simulations to obtain the instrument's polarimetric sensitivity, and
these simulations include photon polarization. For GRB021206, we formally find
a linear polarization degree of 41% (+57% -44%), concluding that the data
quality is insufficient to constrain the polarization degree in this case. We
further applied our analysis to GRB030519B and found again a null result.Comment: 39 pages, 11 figures, accepted for publication by the Astrophysical
Journa
RHESSI as Gamma Ray Burst Polarimeter
The Reuven Ramaty High Energy Solar Spectroscopic Imager
(RHESSI) was designed to measure hard X-rays and Îł-rays from solar flares. With its big detection area and thin side shielding it also proved to be well suited for studying
Gamma Ray Bursts (GRB). Polarization analysis is feasible as well, due to a big modulation factor (MF), though serious constraints on the minimum detectable polarization
(MDP) come from detection efficiency of double scattered photons. More constraints are given by background of accidental and real coincidences
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