A review of AMS-02 and its results after nearly 5 years of operation.

C. Delgado

ICRR, CIEMAT

Outline

• Intuition about charged cosmic rays propagation

• The AMS-02 experiment

• An analysis example

• Results

• Conclusions

BUILDING SOME INTUITION ABOUT COSMIC RAYS PROPAGATION

I. Moskalenko

Building the intution about charged CR propagation

R about 30 kpc H about 2 kpc h about 0.15 kpc Average density n about 5 protons/cm3

Primary sources located in the disk Diffusion due to magnetic field with diffusion coeff. D

R

Building the intution about charged CR propagation

R about 30 kpc H about 2 kpc h about 0.15 kpc Average density n about 5 protons/cm3

Primary sources located in the disk Diffusion due to magnetic field with diffusion coeff. D

R

Except for electrons

𝐹

𝜏𝑒𝑠𝑐

Building the intution about charged CR propagation

• Time scale to reach reach Halo limit and escape:

• Time spent in the disk given a diffusion length L

• Energy loss time scale (synchrotron & IC)

𝑡 𝐿 =1

2𝜋

ℎ𝐿

𝐷

𝑡 (𝐻) ≈ 106 𝑦𝑒𝑎𝑟𝑠

𝜏𝑒𝑠𝑐 𝐻 ≈ 𝐻2

𝐷=

𝐻2

𝐷0𝑅

3𝐺𝑉

0.6𝛽−2

≈ 5 107 𝑦𝑒𝑎𝑟𝑠

𝜏𝑙𝑜𝑠𝑠 ≈ 2 1051𝑇𝑉

𝑅

𝑀

𝑍 𝑚𝑒

2

𝑦𝑒𝑎𝑟𝑠

Building the intution about charged CR propagation

• Effective diffusion length due to fragmentation:

• Secondary to primary ratio

– Kinetic energy per nucleon conserved in fragmentation

𝐿 ≈ 2𝜋

𝑛 𝑐𝛽 𝜎

𝐷

ℎ= 1.5𝛽−3

𝑅

3𝐺𝑉

0.6 𝐴

12

−23

𝑘𝑝𝑐

𝑓𝑜𝑟 𝑝 ≈ 15 𝑅𝐺𝑉

0.6 𝑘𝑝𝑐

𝑓𝑜𝑟 𝐻𝑒 ≈ 6 𝑅𝐺𝑉

0.6 𝑘𝑝𝑐

𝑓𝑜𝑟 𝐶 ≈ 3 𝑅𝐺𝑉

0.6 𝑘𝑝𝑐

𝑁𝑠𝑒𝑐(𝐸𝑘𝑖𝑛 𝐴 )

𝑁𝑝𝑟𝑖𝑚(𝐸𝑘𝑖𝑛 𝐴 )~ ℎ𝐻

𝐷𝑛 𝑐𝛽 𝜎~

𝑛ℎ𝐻

𝐷0𝛽3

𝑅

3𝐺𝑉

−0.6 𝐴

12

23

Dif

fusi

on

par

amet

ers

fro

m

Ast

rop

arti

cle

Ph

ysic

s 3

9–4

0 (

20

12

) 4

4–5

1

I. Moskalenko

Geomagnetic shielding

Longitude [deg]

Lati

tud

e [

de

g]

Geomagnetic shielding vs position of the orbit

THE AMS-02 EXPERIMENT

AMS-02 detector

5m x 4m x 3m 7.5 Tons >300000 channels

AMS ANALYSIS EXAMPLE: HELIUM

For a give rigidity bin, this is the time the Orbit is in a position witha cutoff below the rigidity, times the “live time.”

Explicit verification of the tracker on ground

SOME AMS-02 RESULTS: NUCLEI

He flux

He flux

He vs p fluxes

SOME AMS-02 RESULTS: SECONDARY TO PRIMARY

B/C ratio

SOME AMS-02 RESULTS: ELECTRONS & POSITRONS

Result

e- + e+ flux

CONCLUSIONS

Conclusions

Non uniform diffusion is clearly the case, even more after AMS-02 data. Problems with anti protons: there are too many (maybe a problem with x-section) Positrons /electrons additional source to be found: getting closer to the cutoff. High precission data beyond models precision now.

PreAMS02 data

Cream HEAO

Thank you