Author Topic: AMS-2 (Alpha Magnetic Spectrometer)  (Read 61368 times)

Offline ugordan

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Re: AMS-2 (Alpha Magnetic Spectrometer)
« Reply #60 on: 04/04/2013 08:02 am »

Offline IRobot

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Re: AMS-2 (Alpha Magnetic Spectrometer)
« Reply #61 on: 04/04/2013 11:13 am »
A more critical look at the initial results: http://resonaances.blogspot.com/2013/04/first-results-of-ams-02.html
Thanks, that should put a cork on the pseudo pulsar astronomer.

I like this part:
Quote
There's absolutely no way that measurements of the  positron spectrum may give us a reliable evidence for dark matter: not now, and not anytime soon.

I also like this part although AFAIK there were some sun science made in Skylab...
Quote
The most important thing we learned today is that AMS works and exceeds in precision the previous instruments (which wasn't that obvious: it's the first time a serious experiment is performed on a space station, and besides the mission underwent a dramatic downgrade shortly before the launch).

Offline Chris Bergin

Re: AMS-2 (Alpha Magnetic Spectrometer)
« Reply #62 on: 04/04/2013 01:32 pm »
I've written an article about this, but mainly relating to the mission planning that enabled AMS-02 to actually get to the ISS:

http://www.nasaspaceflight.com/2013/04/endeavours-legacy-ams-02-proving-value/
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Offline Space Pete

Re: AMS-2 (Alpha Magnetic Spectrometer)
« Reply #63 on: 04/04/2013 03:45 pm »
it's the first time a serious experiment is performed on a space station

What the heck is this guy smoking? He's clearly another one of these "I know about science, and so despite the fact that I have done absolutely zero research on ISS science, that makes me qualified to speak about it authoritatively" type people.

Like we needed more of those.... ::)
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Offline arachnitect

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Re: AMS-2 (Alpha Magnetic Spectrometer)
« Reply #64 on: 04/04/2013 05:04 pm »
Well, if nothing else, at least it's something we can point to and say: "This is something the ISS has done that we could not have done elsewhere!"

Didn't Jim say there's no reason AMS couldn't have flown as a free flyer if it had been planned from the start? Is ISS providing anything that a s/c bus couldn't?

While I'm glad AMS flew and ended up on ISS, it's easier to imagine a high-profile "big science" experiment like AMS getting it's own mission than many of the other hosted payloads that have gone to ISS, like SAGE-III or the Robotic Refueling Mission, not to mention things like nanoracks or the cubesats which have hitched rides on COTS/CRS flights.

Offline arkaska

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Re: AMS-2 (Alpha Magnetic Spectrometer)
« Reply #65 on: 04/04/2013 06:46 pm »
it's the first time a serious experiment is performed on a space station

What the heck is this guy smoking? He's clearly another one of these "I know about science, and so despite the fact that I have done absolutely zero research on ISS science, that makes me qualified to speak about it authoritatively" type people.

Like we needed more of those.... ::)

One tip is to actually read the blog-post before you get all wind up ;)

"Résonaances is a particle physics blog from Paris. It's about the latest news and gossips in particle physics and astrophysics. The posts are often spiced with sarcasm, irony, and a sick sense of humor. The goal is to make you laugh; if it makes you think too, that's entirely on your own responsibility..."

http://resonaances.blogspot.se
« Last Edit: 04/04/2013 06:47 pm by arkaska »

Offline eeergo

Re: AMS-2 (Alpha Magnetic Spectrometer)
« Reply #66 on: 04/05/2013 09:45 am »
it's the first time a serious experiment is performed on a space station

What the heck is this guy smoking? He's clearly another one of these "I know about science, and so despite the fact that I have done absolutely zero research on ISS science, that makes me qualified to speak about it authoritatively" type people.

Like we needed more of those.... ::)

One tip is to actually read the blog-post before you get all wind up ;)

"Résonaances is a particle physics blog from Paris. It's about the latest news and gossips in particle physics and astrophysics. The posts are often spiced with sarcasm, irony, and a sick sense of humor. The goal is to make you laugh; if it makes you think too, that's entirely on your own responsibility..."

http://resonaances.blogspot.se

Actually I don't think the remark should be controversial or even satyrical at all, if you read it in its proper context and not isolated. He's just remarking it's the first time a serious experiment [of this kind = particle physics!] is done on a space station (not just the ISS), which happens to be true. Other (major) physics experiments in space stations were either observational astrophysics or from other physics disciplines.
-DaviD-

Online AnalogMan

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Re: AMS-2 (Alpha Magnetic Spectrometer)
« Reply #67 on: 07/06/2013 01:41 am »
Latest update:

New AMS results to be presented at ICRC 2013 at Rio de Janeiro, Brasil
July 5th, 2013
 
We are all looking forward  for  the planned release of several new results from the AMS Collaboration at the  International Cosmic Ray Conference 2013 in Brasil.
 
On July 8th, during a special ICRC  session dedicated to  AMS,  the  Collaboration will present new results on the precision measurement of:  proton, helium, electron, positrons and Boron/Carbon as well as the positron to electron ratio.
 
The data correspond to 24 month of data taking, about 31 billions of trigger recorded by the experiment and transferred to ground.
 
Stay tuned on this page for more news.
http://www.ams02.org/2013/07/new-ams-results-to-be-presented-at-icrc-2013-at-rio-de-janeiro-brasil/

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Re: AMS-2 (Alpha Magnetic Spectrometer)
« Reply #68 on: 01/21/2014 11:04 am »
Latest update:

New AMS results to be presented at ICRC 2013 at Rio de Janeiro, Brasil
July 5th, 2013
 
We are all looking forward  for  the planned release of several new results from the AMS Collaboration at the  International Cosmic Ray Conference 2013 in Brasil.
 
On July 8th, during a special ICRC  session dedicated to  AMS,  the  Collaboration will present new results on the precision measurement of:  proton, helium, electron, positrons and Boron/Carbon as well as the positron to electron ratio.
 
The data correspond to 24 month of data taking, about 31 billions of trigger recorded by the experiment and transferred to ground.
 
Stay tuned on this page for more news.
http://www.ams02.org/2013/07/new-ams-results-to-be-presented-at-icrc-2013-at-rio-de-janeiro-brasil/

So has there been any more information released?
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Offline eeergo

Re: AMS-2 (Alpha Magnetic Spectrometer)
« Reply #69 on: 01/21/2014 11:49 am »
Yes, although there were basically no surprises with respect to the earlier releases. For now there is not enough sensitivity yet to differentiate dark matter models vs other standard explanations. No cutoff has been seen yet. I had the opportunity of attending several AMS-02 conference talks back in September, I can attach some slides from Marco Incagli.

Here, about the positron fraction and its consequences:
« Last Edit: 01/21/2014 11:56 am by eeergo »
-DaviD-

Offline eeergo

Re: AMS-2 (Alpha Magnetic Spectrometer)
« Reply #70 on: 01/21/2014 11:57 am »
Electron and positron fluxes.
-DaviD-

Offline eeergo

Re: AMS-2 (Alpha Magnetic Spectrometer)
« Reply #71 on: 01/21/2014 11:59 am »
Proton and helium fluxes and B/C ratio + summary by W. Xu.
« Last Edit: 01/21/2014 12:02 pm by eeergo »
-DaviD-

Offline Prober

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Re: AMS-2 (Alpha Magnetic Spectrometer)
« Reply #72 on: 01/23/2014 04:01 pm »
While hailing Endeavour, ISS, and AMS let's not forget to give some rare credit to the normally ineffectual US Congress which provided the money and specific direction to NASA to launch AMS which NASA had no plans (or capability) to do before the planned retirement of the shuttle.

Good point thanks for pointing this out.  We should give credit where credit is due.
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Online AnalogMan

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Re: AMS-2 (Alpha Magnetic Spectrometer)
« Reply #73 on: 07/04/2014 07:10 pm »
Came across this recent presentation given by Dr Samuel Ting:

"The Latest Results from The Alpha Magnetic Spectrometer on the International Space Station"
June 17, 2014
http://ams.nasa.gov/Documents/AMS_Publications/NASA%20JUNE-2014C.pdf
(50 slides, 6.8MB)

Not sure it has much that has not already been seen (its not a peer reviewed scientific paper).

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Re: AMS-2 (Alpha Magnetic Spectrometer)
« Reply #74 on: 09/19/2014 04:32 pm »
Latest press release:

New results from the Alpha Magnetic Spectrometer on the International Space Station
September 18th, 2014

The new results on energetic cosmic ray electrons and positrons are announced today. They are based on the first 41 billion events measured with the Alpha Magnetic Spectrometer (AMS) on the International Space Station (ISS).  These results provide a deeper understanding of the nature of high energy cosmic rays and shed more light on the dark matter existence.
 
>Download AMS Collaboration Press Release
 
>Webcast of the seminar at CERN

>High Statistics Measurement of the Positron Fraction in Primary Cosmic Rays of 0.5–500 GeV with the Alpha Magnetic Spectrometer on the International Space Station

>Electron and Positron Fluxes in Primary Cosmic Rays Measured with the Alpha Magnetic Spectrometer on the International Space Station

AMS has analyzed 41 billion primary cosmic ray events.  Of these, 10 million have been identified as electrons and positrons.  AMS has measured the positron fraction (ratio of the number of positrons to the combined number of positrons and electrons) in the energy range 0.5 to 500 GeV.  We have observed that the energy at which the fraction starts to quickly increase is 8 GeV (see Figure 1) indicating the existence of a new source of positrons. Figure 2 shows that the exact rate at which the positron fraction increases with energy has now been accurately determined and the fraction shows no observable sharp structures.  The energy at which the positron fraction ceases to increase (corresponding to the turning point energy at which the positron fraction reaches its maximum) has been measured to be 275+32 GeV as shown in Figure 2 (upper plot). This is the first experimental observation of the positron fraction maximum after half a century of cosmic rays experiments. The excess of the positron fraction is isotropic within 3% strongly suggesting the energetic positrons may not be coming from a preferred direction in space.

[press release continues with lots more detail … ]
http://www.ams02.org/2014/09/new-results-from-the-alpha-magnetic-spectrometer-on-the-international-space-station/

Offline TomH

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Offline russianhalo117

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Re: AMS-2 (Alpha Magnetic Spectrometer)
« Reply #76 on: 01/06/2017 04:51 pm »
Bump for 2016 release of 5 Year findings report and forward research plan:
LINK: http://www.ams02.org/2016/12/the-first-five-years-of-the-alpha-magnetic-spectrometer-on-the-international-space-station/


The First Five Years of the Alpha Magnetic Spectrometer on the International Space Station

December 8th, 2016

Unlocking the Secrets of the Cosmos: The First Five years of AMS on the International Space Station

>> Download the AMS Collaboration press release

The Alpha Magnetic Spectrometer (AMS) Collaboration announces the fifth anniversary of the AMS Experiment on the International Space Station (ISS) and summarizes its major scientific results to date.

The AMS Experiment (shown in Figure 1) is the most sensitive particle detector ever deployed in space and is exploring a new and exciting frontier in physics research. As a magnetic spectrometer, AMS is unique in physics research as it studies charged particles and nuclei in the cosmos before they are annihilated in the Earth’s atmosphere. The improvement in accuracy over previous measurements is made possible through its long duration time in space, large acceptance, built in redundant systems and its thorough calibration in the CERN test beam. These features enable AMS to analyze the data to an accuracy of ~1%. The first five years of data from AMS on the International Space Station are beginning to unlock the secrets of the cosmos.

Since its installation on the ISS in May 2011, AMS has collected data from more than 90 billion cosmic rays with up to multi-TeV energies and published its major physics results in Physical Review Letters.

A note about cosmic rays: As the products of exploding supernovae, primary cosmic rays can travel for millions of years in the galaxy before reaching AMS. Secondary cosmic rays come from the interaction of primary cosmic rays with the interstellar media. Uniquely positioned on the International Space Station, AMS studies cosmic rays passing through its precision detectors, to define the charge, energy, and momentum of the passing particles in order to obtain an understanding of dark matter, the existence of complex antimatter in space, the properties of primary and secondary cosmic rays as well as new, unexpected phenomena. These are among the fundamental issues in modern physics.

There are hundreds of different kinds of charged elementary particles.   Only four of them – electrons, protons, positrons and antiprotons – have infinite lifetimes so they can travel through the cosmos forever. Electrons and positrons have much smaller mass than protons and antiprotons so they lose much more energy in the galactic magnetic field due to synchrotron radiation.

As shown in Figure 2, AMS has observed that the electron flux and positron flux display different behaviors both in their magnitude and in their energy dependence.

Most surprisingly, from 60 to 500 GeV, positrons, protons and antiprotons display identical momentum dependence but electrons exhibit a totally different dependence as shown in Figure 3. The reason that this observation is surprising is that both electrons and positrons lose energy (or momentum) equally when travelling through the galactic magnetic field and at a much higher rate than protons or antiprotons.

There has been much interest over the last few decades in understanding the origin and nature of dark matter. When particles of dark matter collide, they produce energy that transforms into ordinary particles, such as positrons and antiprotons. The characteristic signature of dark matter is an increase with energy followed by a sharp drop off at the mass of dark matter as well as an isotropic distribution of the arrival directions of the excess positrons and antiprotons.

Figure 4 shows the latest results from AMS on the positron flux. As seen from the figure, after rising from 8 GeV above the rate expected from cosmic ray collisions, the spectrum exhibits a sharp drop off at high energies in excellent agreement with the dark matter model predictions with a mass of ~1 TeV. There is great interest in the physics community on the AMS measurements of elementary particles. For example, an alternative speculation for positron spectrum is that this rise and drop off may come from new astrophysical phenomena such as pulsars.

AMS has also studied the antiproton to proton ratio. The excess in antiprotons observed by AMS cannot easily be explained as coming from pulsars but can be explained by dark matter collisions or by other new astrophysics models. Antiprotons are very rare in the cosmos. There is only one antiproton in 10,000 protons therefore a precision experiment requires a background rejection close to 1 in a million. It has taken AMS five years of operations to obtain a clean sample of 349,000 antiprotons. Of these, AMS has identified 2200 antiprotons with energies above 100 billion electron volts. Experimental data on cosmic ray antiprotons are crucial for understanding the origin of antiprotons in the cosmos and for providing insight into new physics phenomena.

Protons are the most abundant particles in cosmic rays. AMS has measured the proton flux to an accuracy of 1% with 300 million protons and found that the proton flux cannot be described by a single power law, as had been assumed for decades, and that the proton spectral index changes with momentum.

AMS contains seven instruments with which to independently identify different elementary particles as well as nuclei. Helium, lithium, carbon, oxygen and heavier nuclei up to iron have been studied by AMS. It is believed that helium, carbon and oxygen were produced directly from primary sources in supernova remnants whereas lithium, beryllium and boron are believed to be produced from the collision of primary cosmic rays with the interstellar medium. Primary cosmic rays carry information about their original spectra and propagation, and secondary cosmic rays carry information about the propagation of primary and secondary cosmic rays and the interstellar medium.

Helium is the second most abundant cosmic ray. Helium has been studied over the past century. Although lithium is a secondary cosmic ray, its spectrum behaves similarly to protons and helium in that none of the three fluxes can be described by a single power law and they do change their behavior at the same energy.

Since protons, helium, carbon and oxygen are primary cosmic rays and produced at the same sources; thus their flux ratios should be rigidity independent. Rigidity is momentum per unit charge and is the metric by which magnetic fields, such as those experienced by cosmic rays between their origin and AMS, act on charged particles. From the AMS measurements, for carbon-to-helium and for carbon-to-oxygen these ratios are, indeed, independent of rigidity, i.e., flat, as expected. Unexpectedly, the proton-to-helium flux ratio drops quickly but smoothly with rigidity.

Other secondary cosmic rays being measured by AMS include boron and beryllium. The unstable isotope of beryllium, 10Be, has a half-life of 1.5 million years and decays into boron. The Be/B ratio therefore increases with energy due to time dilation when the Be approaches the speed of light. Hence, the ratio of beryllium to boron provides information on the age of the cosmic rays in the galaxy. From this, AMS has determined that the age of cosmic rays in the galaxy is ~12 million years.

The flux ratio between secondary cosmic rays (boron) and primary cosmic rays (carbon) provides information on propagation and the average amount of interstellar material (ISM) through which the cosmic rays travel in the galaxy. Cosmic ray propagation is commonly modeled as a fast moving gas diffusing through a magnetized plasma. Various models of the magnetized plasma predict different behavior of the boron-to-carbon (B/C) flux ratio. Remarkably, above 65 GeV, the B/C ratio measured by AMS is well described by a single power law B/C= kRd with d = -0.333±0.015. This is in agreement with the Kolmogorov turbulence model of magnetized plasma where d = -1/3 asymptotically. Of equal importance, the B/C ratio does not show any significant structures in contrast to many cosmic ray models.

The carbon and oxygen fluxes, which are both primary cosmic rays, and the boron, lithium, and beryllium fluxes, which are secondary, have characteristically different rigidity dependences.

The Big Bang origin of the Universe requires that matter and antimatter be equally abundant at the very hot beginning of the universe. The search for the explanation for the absence of antimatter in a complex form is known as Baryogenesis. Baryogenesis requires both a strong symmetry breaking and a finite proton lifetime. Despite the outstanding experimental efforts over many years, no evidence of strong symmetry breaking nor of proton decay have been found. Therefore, the observation of a single anti-helium event in cosmic rays is of great importance.

In five years, AMS has collected 3.7 billion helium events (charge Z = +2). To date we have observed a few Z = -2 events with mass around 3He. At a rate of approximately one antihelium candidate per year and a required signal (antihelium candidates) to background (helium) rejection of one in a billion, a detailed understanding of the instrument is required. In the coming years, with more data, one of our main efforts is to ascertain the origin of the Z = -2 events.

In five years, AMS on the ISS has recorded more than 90 billion cosmic ray events. The latest AMS measurements of the positron spectrum and positron fraction, the antiproton/proton ratio, the behavior of the fluxes of electrons, positrons, protons, helium and other nuclei provide precise and unexpected information on the production, acceleration and propagation of cosmic rays. The accuracy and characteristics of the data, simultaneously from many different types of cosmic rays require the development of a comprehensive model. In the coming years, with more data, one of our main efforts is to ascertain the origin of the Z = -2 events.

Most importantly, AMS will continue to collect and analyze data for the lifetime of the Space Station. As the results to date have demonstrated, whenever a precision instrument such as AMS is used to explore the unknown, new and exciting discoveries can be expected.

The results of the first five year have been presented on December the 8th, 2016, at 17:00 (Geneva time) in a CERN Colloquium:

https://indico.cern.ch/event/592392/

------------------------------------------

Captions for figures in order of the Summary of the latest findings report:
Figure 1. From its vantage point ~240 miles (400 km) above the Earth, the Alpha Magnetic Spectrometer (AMS) collects data from passing cosmic rays from primordial sources in the universe before they pass through the Earth’s atmosphere.

Figure 2. The electron flux and the positron flux are different in their magnitude and energy dependence.

Figure 3. The positron, proton, and antiproton spectra have identical momentum dependence from 60 to 500 GeV. The electron spectrum exhibits a totally different behavior, it decreases much more rapidly with increasing momentum.

Figure 4. The current AMS positron flux measurement compared with theoretical models.
« Last Edit: 01/06/2017 04:54 pm by russianhalo117 »

Online catdlr

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Re: AMS-2 (Alpha Magnetic Spectrometer)
« Reply #77 on: 10/14/2017 02:35 am »
October 13, 2017
MEDIA ADVISORY M17-117

NASA Johnson Space Center Invites Media to Screening of Documentary on Alpha Magnetic Spectrometer
Media are invited to attend the screening of “AMS: The Fight for Flight,” a NASA documentary about the Alpha Magnetic Spectrometer (AMS) and its principal investigator, Nobel laureate Samuel Ting.

The one-hour historical documentary, to be shown at 6 p.m. Oct. 17 at Space Center Houston, showcases the capabilities of the International Space Station as a science platform. It follows the development of the Alpha Magnetic Spectrometer, a science instrument studying the fundamental nature of the universe, through Ting’s efforts. The story focuses on the dedication of Ting, former NASA officials and Congress to fly it to the station on the next to last space shuttle mission.

The audience will include Johnson Space Center employees and special invited guests. Media planning to attend must contact the Johnson Space Center newsroom at 281-483-5111 no later than 5 p.m. Oct. 16.

International Space Station Program Manager Kirk Shireman will welcome attendees and Ting will provide a short presentation. Media will be able to conduct individual interviews after the event.

Originally proposed in 1994 by Ting, an MIT professor of Physics, the AMS was built by over 600 physicists and engineers all over the world. One of the most complex physics experiments ever launched into space, the AMS searches for evidence of dark matter and antimatter in the universe. It’s history spans 23 years from the drawing table to its final home on the space station.

    
Press Contacts

Gary Jordan
Johnson Space Center, Houston
281-483-5111
[email protected]

    
NASA Johnson Space Center news releases and other information are available automatically by sending an e-mail message with the subject line subscribe to [email protected] To unsubscribe from the list, send an e-mail message with the subject line unsubscribe to [email protected]

Other NASA news releases and information are available automatically by sending an e-mail message with the subject line subscribe to [email protected].

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Offline eeergo

Re: AMS-2 (Alpha Magnetic Spectrometer)
« Reply #78 on: 11/21/2017 12:20 pm »
Interesting set of (contradictory) papers on the main result by AMS-02:

http://science.sciencemag.org/content/358/6365/911

https://journals.aps.org/prd/abstract/10.1103/PhysRevD.96.103013

The HAWC Earth-based Cherenkov telescopes have performed precision measurements of TeV-scale gamma flux from pulsars, correlated with positron flux. The first paper concludes pulsars are insufficient to explain the AMS-02/PAMELA/CALET (and, in the near future, one would expect ISS-CREAM) positron excess observed, strengthening the need to invoke a more exotic solution to the excess (dark matter, but also others).

However :) the second paper, with the same data, does just the contrary: for them, the excess is compatible with the larger high-energy gamma flux measured.

So I'd say the conclusion for now is that the jury is still out!
-DaviD-

Offline eeergo

Re: AMS-2 (Alpha Magnetic Spectrometer)
« Reply #79 on: 05/03/2018 12:29 am »
"AMS looks at Galactic Cosmic Rays" - CERN/EP Newsletters - by Panos Charito

Quote
Highly energetic particles consist of essentially every element ranging from hydrogen, accounting for approximately 89% of the GCR spectrum. The idea that Supernova Remnant (SNR) shocks are the primary sites of CR acceleration in the Galaxy is what is generally referred to as the ”Supernova remnant paradigm for the origin of Cosmic Rays”. This paradigm has been under scrutiny now for about 50 years, but only in the last few years some clear evidence in its favour has been found. [...]

AMS provides a continuous stream of time-resolved and multichannel Cosmic Ray data that set new objectives, namely: (i) to advance solar modulation observations of Cosmic Ray particles and antiparticles, and (ii) to develop improved and measurement-validated models of Cosmic Ray transport in the heliosphere.

Moreover, the new data allow to understand the puzzling anomalies detected in the energy spectra of CR proton and helium nuclei while also maintaining the universality of the dominant diffusive-shock acceleration mechanism.  In this model, the p/He anomaly is explained by a flux transition between two source components that have different injection spectra and composition.

Another important topic is the recent observation of an eight-month time lag in solar modulation of Cosmic Rays. This effect reveals important properties on the dynamics of the formation and changing conditions of the heliospheric plasma. Crucial tests can be performed by AMS via monthly-resolved measurements of these ratios, or even better, by measurements of individual particle fluxes for protons, antiprotons, electrons and positrons under both polarity conditions and across the magnetic reversal. This demonstrates that time-dependent measurements on CR antimatter can provide precious information on the physics of the heliosphere. Finally, understanding the charge-sign dependence of Cosmic Ray modulation is also essential to search for dark matter signatures in Cosmic Ray fluxes.

https://ep-news.web.cern.ch/content/ams-looks-cosmic-galactic-rays
« Last Edit: 05/03/2018 12:29 am by eeergo »
-DaviD-

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