Alpha Magnetic Spectrometer Research Articles

Effects of the rotation of International Space Station main radiator on suppressing thermal anomaly of Alpha Magnetic Spectrometer caused by flight attitude adjustment

In a previous study, we found that the temperature anomaly might occur at the Alpha Magnetic Spectrometer mounted on the International Space Station under its flight attitude adjustment during on-orbit operation. Accordingly, this article puts forward a novel thermal control method applied for suppressing that temperature anomaly by utilizing the thermal effect of the maneuver of International Space Station starboard radiator rotation on Alpha Magnetic Spectrometer. For that purpose, the variations of external heat flux and temperature of the Alpha Magnetic Spectrometer main radiators with the starboard radiator rotation under the flight attitude adjustment are numerically investigated, while the thermal control performances on reducing the temperature anomaly occurrence are comparatively analyzed. Results show that rotating the starboard radiator can lead to a maximum increase in external heat flux of 11.4% and a maximum decrease of 5.7%, respectively. At the starboard radiator positions with the minimum external heat flux, the temperature will decrease by 0.4–52.2%. For the temperature anomaly caused by the attitude adjustment, the starboard radiator rotation presents a good thermal control performance of delaying its occurrence time by 2–28.1% and even avoiding its occurrence at 3 kind of cases.

Deciphering the Local Interstellar Spectra of Secondary Nuclei with the Galprop/Helmod Framework and a Hint for Primary Lithium in Cosmic Rays.

Local interstellar spectra (LIS) of secondary cosmic-ray (CR) nuclei, lithium, beryllium, boron, and partially secondary nitrogen, are derived in the rigidity range from 10 MV to ~200 TV using the most recent experimental results combined with state-of-the-art models for CR propagation in the Galaxy and in the heliosphere. The lithium spectrum appears somewhat flatter at high energies compared to other secondary species, which may imply a primary lithium component. Two propagation packages, GALPROP and HelMod, are combined to provide a single framework that is run to reproduce direct measurements of CR species at different modulation levels, and at both polarities of the solar magnetic field. An iterative maximum-likelihood method is developed that uses GALPROP-predicted LIS as input to HelMod, which provides the modulated spectra for specific time periods of the selected experiments for the model-data comparison. The proposed LIS accommodates the low-energy interstellar spectra measured by Voyager 1, the High Energy Astrophysics Observatory-3 (HEAO-3), and the Cosmic Ray Isotope Spectrometer on board of the Advanced Composition Explorer (ACE/CRIS), as well as the high-energy observations by the Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics (PAMELA), Alpha Magnetic Spectrometer-02 (AMS-02), and earlier experiments that are made deep in the heliosphere. The interstellar and heliospheric propagation parameters derived in this study are consistent with our earlier results for propagation of CR protons, helium, carbon, oxygen, antiprotons, and electrons.

Observation of Complex Time Structures in the Cosmic-Ray Electron and Positron Fluxes by the Alpha Magnetic Spectrometer on the ISS

We present high-statistics, precision measurements by AMS of the detailed time and energy dependence of the primary cosmic-ray electron and positron fluxes over 79 Bartels rotations from May 2011 to May 2017 in the energy range from 1 to 50 GeV. For the first time, the charge-sign dependent modulation during the solar maximum has been investigated in detail by leptons alone. We report the observation of short-term structures on the timescale of months which are not visible in the positron-to-electron flux ratio. The precision measurements across the solar polarity reversal show that the ratio exhibits a smooth transition over ˜ 800 days from one value to another.

Anisotropy of cosmic ray fluxes measured with AMS-02 on the ISS

A measurement of the cosmic ray anisotropy on the arrival directions of elementary particles (electrons, positrons and protons) and light nuclei (helium, carbon and oxygen) has been performed in galactic coordinates by the Alpha Magnetic Spectrometer onboard the International Space Station. The analysis is based on the sample of events collected in the first 6.5 years (electrons and positrons), and 7.5 (protons, helium, carbon and oxygen) of data taking. The results are consistent with isotropy for all cosmic ray species and upper limits on the dipole amplitude have been computed. In particular, 95% credible interval upper limits of δ < 1.9% and δ < 0.5% are obtained for positrons and electrons, respectively, above 16 GeV. On the other hand, the upper limits of protons, helium, carbon and oxygen above 200 GV are found to be δ < 0.38%, δ < 0.36%, δ < 1.9% and δ < 1.7%, respectively.

Measurements of nuclear interaction cross sections with the Alpha Magnetic Spectrometer on the International Space Station

Precise knowledge of nuclear interactions with the detector materials is crucial for the accurate measurements of cosmic-ray nuclei fluxes. We have measured the interaction cross sections on carbon target for various nuclear species with charge 2≤Z≤16 in a wide rigidity (momentum/charge) range from a few GV to TV, using cosmic-ray nuclei events collected by the Alpha Magnetic Spectrometer. The properties of the measured nuclear interaction cross sections are discussed.

Possible Evidence for the Gluon Condensation Effect in Cosmic Positron and Gamma-Ray Spectra

Abstract The gluon condensation (GC) effect in cosmic proton–proton collisions at high energy is used to explain an excess in the positron spectrum observed by the Alpha Magnetic Spectrometer. We find that this excess may originate from the GC effect in Tycho's supernova remnant.

AMS-02 beryllium data and its implication for cosmic ray transport

The flux of unstable secondary cosmic ray nuclei, produced by spallation processes in the interstellar medium, can be used to constrain the residence time of cosmic rays inside the Galaxy. Among them, $^{10}$Be is especially useful because of its relatively long half-life of 1.39 Myr. In the framework of the diffusive halo model we describe cosmic ray transport taking into account all relevant interaction channels and accounting for the decay of unstable secondary nuclei. We then compare our results with the data collected by the Alpha Magnetic Spectrometer (AMS-02) on board the International Space Station for the flux ratios Be/C, B/C, Be/O, B/O, C/O and Be/B as well as C, N and O absolute fluxes. These measurements, and especially the Be/B ratio, allow us to single out the flux of $^{10}$Be and infer a best fit propagation time of CRs in the Galaxy. Our results show that, if the cross sections for the production of secondary elements through spallation are taken at face value, AMS-02 measurements are compatible with the standard picture based on CR diffusion in a halo of size $H \gtrsim 5$ kpc. Taking into account the uncertainties in the cross sections, this conclusion becomes less reliable, although still compatible with the standard picture. Implications of our findings for alternative models of CR transport are discussed.

Numerical investigation on the thermal performance of Alpha Magnetic Spectrometer main radiators under the operation of International Space Station

The thermal environment of the space-borne instruments can be affected by their carriers. Investigation on those thermal effects has great importance for those payloads operating safely and stably. In the current work, the influences of the operation of International Space Station flight attitude adjustment on the thermal performance of the Alpha Magnetic Spectrometer main radiators are studied by numerical simulations. For that purpose, the thermal network model is developed and validated by the theoretical calculation from the mathematical model, based on which, the external heat flux absorbed and the temperature response characteristics under the three most frequent attitude adjustments are further studied. By the results, the error between the two models is less than 18.2% which proves the validation of the developed numerical model. The external heat flux varies obviously when changing the flight attitude and even reaches its maximum of 480 W/m2. The temperatures respond accordingly and may even cause the temperature anomalies in 44.8% of the selected cases with the minimum occurrence time of 6235 s. Moreover, the areas with the most drastic temperature variations are always located at the upper-right and the bottom positions of AMS main radiators, which is independent of the flight attitude adjustment.

Offline Software Management of the AMS experiment

The Alpha Magnetic Spectrometer (AMS) is a particle physics experiment installed and operating aboard the International Space Station (ISS) from May 2011 and expected to last through 2028 and beyond. The AMS offline software is used for data reconstruction, Monte-Carlo simulation and physics analysis. This paper presents how we manage the offline software, including the version control, automatic integration, automatic deployment, and the distribution.

Thermal analysis and optimization of the electronic crates of Alpha Magnetic Spectrometer

Alpha Magnetic Spectrometer (AMS-02) is a particle-physics detector from a module attached to the outside of the International Space Station (ISS). The temperature of the components in AMS-02 must be kept within their different operational ranges but also must be stable over both time and volume. Thermal modeling and simulations for the radiator and the electronic crates of AMS-02 were carried out by applying the Crank–Nicholson implicit solution. Based on reducing the temperature gradient of the radiator and the mass of the thermal control system, the layout of the heat pipes in the radiator was optimized to solve the overheating issue of the electronic crates. The non-operational and operational temperature dissipation for the thermal control system was calculated. The analysis results for the radiator and the electronic crates can meet the running requirements of AMS-02 on the ISS.

The Official Website of the AMS Experiment

The Alpha Magnetic Spectrometer (AMS-02) is a particle physics experiment installed on board the International Space Station (ISS). It has been operating since May 2011 and is expected to continue through 2028 or beyond. The AMS collaboration seeks to store, manage and present its research results as well as details about the detector and operations. An open-source content management framework is utilized as the platform to build the website. This platform allows management of a variety of information, such as institutes in the collaboration, physics results, publications, academic events, etc. This note discusses the motivation, strategy, infrastructure, web design techniques, custom modules, data sharing plan, and day-to-day operation. The resulting website is located at https://ams02.space.

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

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 &amp;gt;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.

Properties of Cosmic Helium Isotopes Measured by the Alpha Magnetic Spectrometer.

Precision measurements by the Alpha Magnetic Spectrometer (AMS) on the International Space Station of ^{3}He and ^{4}He fluxes are presented. The measurements are based on 100million ^{4}He nuclei in the rigidity range from 2.1 to 21GV and 18million ^{3}He from 1.9 to 15GV collected from May 2011 to November 2017. We observed that the ^{3}He and ^{4}He fluxes exhibit nearly identical variations with time. The relative magnitude of the variations decreases with increasing rigidity. The rigidity dependence of the ^{3}He/^{4}He flux ratio is measured for the first time. Below 4GV, the ^{3}He/^{4}He flux ratio was found to have a significant long-term time dependence. Above 4GV, the ^{3}He/^{4}He flux ratio was found to be time independent, and its rigidity dependence is well described by a single power law ∝R^{Δ} with Δ=-0.294±0.004. Unexpectedly, this value is in agreement with the B/O and B/C spectral indices at high energies.

Design and application of thermal mass flow meter in space

Abstract This paper presents a thermal mass flow meter designed to measure the liquid CO 2 mass flow rate in an upgraded mechanically pumped two-phase cooling system for the experiment of Alpha Magnetic Spectrometer (AMS-02) on the International Space Station. A computational fluid dynamics model is built to investigate the fluid flow and heat transfer process and to finalize the design. Experimental results under steady-state and transient-state are obtained in a thermal vacuum chamber simulating the space environment to qualify the design and performance. Results show the mass flow predictions are consistent with the direct measurements of a Coriolis flow meter within 10% over a flow range from 1.5 g/s to 3.5 g/s. The designed flow meter shows a potential application in the fluid flow control for space thermal cooling systems.

Investigation on the performance of the thermal blanket on the Transition Radiation Detector gas system of Alpha Magnetic Spectrometer

Abstract Temperature anomaly has the possibility to most quickly occur on the gas circulating pumps of the Transition Radiation Detector (TRD) gas system according to the temperature records of the Alpha Magnetic Spectrometer (AMS) on the International Space Station (ISS). A thermal blanket has been taken as an effective response measure. In this paper, temperature variations of the TRD gas system with β angle before and after installing the thermal blanket are studied and the occurrence laws of the temperature anomaly are determined. Results show that the temperature anomalies are concentrated respectively on the β intervals of − 65 ° , − 28 ° , − 25 ° , + 28 ° , and + 44 ° , + 75 ° before installing the thermal blanket. Installation of the thermal blanket can effectively solve the temperature anomalies in the β interval of − 60 ° , + 60 ° but not in the β intervals of − 75 ° , − 60 ° and + 60 ° , + 75 ° . Then the causes of the temperature anomalies on TRD gas system are investigated based on the on-orbit temperature records. We find the ISS maneuver is an important reason. For the temperature anomalies that may still tend to occur after installing the thermal blanket, the appropriate temperature control suggestions are proposed, which can provide insights into the long-term operation of the AMS and design of the future payload.

Thermal analysis on Alpha Magnetic Spectrometer main radiators under the flight attitude adjustment of International Space Station

Thermal environments of the spaceborne instruments applied for space experiments and space explorations are affected by the maneuvers of the carrier itself, those effects should be taken into account for the designing, manufacturing and long-term stable operation of the spaceborne instruments. In this paper, the mathematical model with three angle variables is established to determine the thermal radiation processes under various attitudes of International Space Station. The results reveal that only the variations of two angles can affect the radiative heat transfer of the Alpha Magnetic Spectrometer main radiators. Based on that, the thermal impacts of the International Space Station attitude adjustments on the main radiators of Alpha Magnetic Spectrometer are numerically investigated in thermal network method, the variation regularities of the external heat flux and the corresponding temperature response are further determined. Results show that the external heat flux has the largest variation at the extreme β angle with the maximum difference of 384 W/m2 on RAM radiator of Alpha Magnetic Spectrometer. After the maneuver of the attitude adjustment, a total of 42% cases have the possibility of temperature anomalies with the occurrence time ranging from 6235 s to 73897 s.

Comparison of space radiation GCR models to AMS heavy ion data

Galactic cosmic rays (GCR) are a constant source of radiation that constitutes one of the major hazards during deep space exploration missions for both astronauts and hardware. In this work, GCR models commonly used by the space radiation protection community are compared with recently published high-precision, high-resolution measurements of cosmic ray lithium, beryllium, boron, carbon, nitrogen, and oxygen fluxes along with their ratios (Li/B, Li/C, Li/O, Be/B, Be/C, Be/O, B/C, B/O, C/O, N/B, N/O) from the Alpha Magnetic Spectrometer (AMS). All of the models were developed and calibrated prior to the publication of this AMS data, therefore this is an opportunity to validate the models against an independent data set. This paper is a compliment to the previously published comparison of GCR models with AMS hydrogen, helium, and the boron-to-carbon ratio (Norbury et al., 2018).

Antiproton flux and properties of elementary particle fluxes in primary cosmic rays measured with the Alpha Magnetic Spectrometer on the International Space Station

Precision measurements by AMS of the antiproton flux and the antiproton-to-proton flux ratio in primary cosmic rays in the absolute rigidity range from 1 to 525 GV is presented, together with the fluxes and flux ratios of charged elementary particles in cosmic rays up to 1 TV. In the absolute rigidity range 60–500 GV, the antiproton p¯, proton p and positron e+ fluxes are found to have nearly identical rigidity dependence and the electron e- flux exhibits different rigidity dependence. From 60GV to 500 GV, the p¯/p,p¯/e+ and p/e+ flux ratios are rigidity independent. These AMS measurements continue to reveal important properties of cosmic ray elementary particle fluxes and provide invaluable input towards understanding the origin of many observed unexpected phenomena.

Improvement in the 3D shower shapes description in the Monte Carlo simulation for a lead-scintillating fiber electromagnetic calorimeter

The lead-scintillating fiber electromagnetic calorimeter (ECAL) of the Alpha Magnetic Spectrometer measures the energy of positrons/electrons and separates them from hadrons. The electromagnetic shower shapes from Monte Carlo (MC) simulation and data show disagreement. Tuning the MC to make the shower shapes from MC and data agree with each other. The tuning is based on a 3D electromagnetic shower model. After tuning, the electromagnetic shower shapes are well described by MC up to TeV. As a result, the output of ECAL electron/proton separation estimator, ECAL BDT, shows that MC and data are in good agreement. The proton rejection power of the ECAL BDT trained with MC electron samples is improved by a factor of 5 at $$\sim \,800\,\hbox {GeV}$$ compared to the one trained with data.

LAA: a project using dedicated funding to develop technology for high-energy physics experiments

In the mid-1980s, the cost of investment in infrastructure for particle accelerators and colliders at the highest energy had risen to such level that the host laboratory (CERN) could no longer afford the cost of development of new detector technology required for the experiments. Large particle colliders were identified by the tools of the future for high-energy physics research, and a long-term view of their development was already conjured up in the late 1970s. It was based on this appraisal that a separate project, called LAA, which addresses the development of the technologies that are required to fully exploit the potential of the new infrastructure, was conceived. The project, specifically funded by the Italian government, centers on advanced microelectronics, and it is largely thanks to this development that the experiments at the large hadron collider (LHC) at CERN were equipped with performant detectors. Some of this equipment features in (i) the Italian School project to observe Extreme Energy Events (EEE), (ii) the Alpha Magnetic Spectrometer (AMS) experiment in the International Space Station and (iii) the time-of-flight (TOF) detector of the LHC heavy ion experiment ALICE at CERN. Several spin-offs for applications in medical instrumentation and advanced electronics were also initiated by development in the framework of the LAA project. The project also covers development work on superconductors and high field superconducting magnets for a future very LHC. The impact of LAA on technology is widely acknowledged.