Precision measurements by the Alpha Magnetic Spectrometer (AMS) on the International Space Station of the deuteron ( D ) flux are presented. The measurements are based on 21 × 10 6 D nuclei in the ...rigidity range from 1.9 to 21 GV collected from May 2011 to April 2021. We observe that over the entire rigidity range the D flux exhibits nearly identical time variations with the p , He 3 , and He 4 fluxes. Above 4.5 GV, the D / He 4 flux ratio is time independent and its rigidity dependence is well described by a single power law ∝ R Δ with Δ D / He 4 = − 0.108 ± 0.005 . This is in contrast with the He 3 / He 4 flux ratio for which we find Δ He 3 / He 4 = − 0.289 ± 0.003 . Above ∼ 13 GV we find a nearly identical rigidity dependence of the D and p fluxes with a D / p flux ratio of 0.027 ± 0.001 . These unexpected observations indicate that cosmic deuterons have a sizable primarylike component. With a method independent of cosmic ray propagation, we obtain the primary component of the D flux equal to 9.4 ± 0.5 % of the He 4 flux and the secondary component of the D flux equal to 58 ± 5 % of the He 3 flux. Published by the American Physical Society 2024
We present the precision measurements of 11 years of daily cosmic positron fluxes in the rigidity range from 1.00 to 41.9 GV based on 3.4×10^{6} positrons collected with the Alpha Magnetic ...Spectrometer (AMS) aboard the International Space Station. The positron fluxes show distinctly different time variations from the electron fluxes at short and long timescales. A hysteresis between the electron fluxes and the positron fluxes is observed with a significance greater than 5σ at rigidities below 8.5 GV. On the contrary, the positron fluxes and the proton fluxes show similar time variation. Remarkably, we found that positron fluxes are modulated more than proton fluxes with a significance greater than 5σ for rigidities below 7 GV. These continuous daily positron fluxes, together with AMS daily electron, proton, and helium fluxes over an 11-year solar cycle, provide unique input to the understanding of both the charge-sign and mass dependencies of cosmic rays in the heliosphere.
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 106 is reached by identifying converted bremsstrahlung photons emitted from positrons.
A brief description of the physics research program implemented with an alpha magnetic spectrometer (AMS detector) by a large-scale international collaboration on board the International Space ...Station is presented. The features of the experimental facility under construction are given, along with some results obtained during the test flight of the prototype spectrometer on board a space shuttle.
The variety of isotopes in cosmic rays allows us to study different aspects of the processes that cosmic rays undergo between the time they are produced and the time of their arrival in the ...heliosphere. In this paper, we present measurements of the isotopic ratios 2H/4He, 3He/4He, 6Li/7Li, 7Be/(9Be+10Be), and 10B/11B in the range 0.2-1.4 GeV of kinetic energy per nucleon. The measurements are based on the data collected by the Alpha Magnetic Spectrometer, AMS-01, during the STS-91 flight in 1998 June.
Measurement of the chemical and isotopic composition of cosmic rays is essential for the precise understanding of their propagation in the galaxy. While the model parameters are mainly determined ...using the B/C ratio, the study of extended sets of ratios can provide stronger constraints on the propagation models. In this paper, the relative abundances of light-nuclei lithium, beryllium, boron, and carbon are presented. The secondary-to-primary ratios Li/C, Be/C, and B/C have been measured in the kinetic energy range 0.35-45 GeV nucleon--1. The isotopic ratio 7Li/6Li is also determined in the magnetic rigidity interval 2.5-6.3 GV. The secondary-to-secondary ratios Li/Be, Li/B, and Be/B are also reported. These measurements are based on the data collected by the Alpha Magnetic Spectrometer AMS-01 during the STS-91 space shuttle flight in 1998 June. Our experimental results are in substantial agreement with other measurements, where they exist. We describe our light-nuclei data with a diffusive-reacceleration model. A 10%-15% overproduction of Be is found in the model predictions and can be attributed to uncertainties in the production cross-section data.
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