HIGH-ENERGY PARTICLE ACCELERATOR

No, not the LHC

By: Nicolas Scozzaro

INTRODUCTION

What particles does the sun accelerate, and how?

What are the principles of detecting particles accelerated by the sun, especially x-rays and gamma-rays?

TWO ACCELERATION PROCESSES: Flares

Coronal mass ejections (CME’s)

(Lin, 2000)

TWO MAIN TYPES OF SOLAR EVENTS

Solar flares and CME’s can occur together

Or they can occur individually

FLARES Release 1032 – 1033 ergs over the course of

100-1000 seconds Conversion? 1 erg = 100 nanojoules (1*10-7 J) => 1025 – 1026

J 1 J = eV => 6.24*1043 – 1044 eV

For comparison, total world energy use for 2008 was about 5*1020 J

WHAT DO FLARES ACCELERATE? Electrons

Most gain 10’s of keV from acceleration Some gain up to 100’s of MeV

Ions (H, He, heavier elements) Most gain a few MeV Some gain up to 10’s of GeV

HOW? Magnetic reconnection

SPECTROSCOPY

CORONAL MASS EJECTION Huge bubbles of gas threaded with magnetic field

lines On average ~ 1012kg Ejection velocities: 20 – 3200 km/s Angular spread ~ 100 degrees Can drive a shock wave, dangerous to astronauts,

sensitive instruments, etc.

http://solarscience.msfc.nasa.gov/images/c2_1mth.mpg

http://www.youtube.com/watch?v=ilhrR2jQSqM&feature=related Sounding Rockets

Satellites

HOW DO WE STUDY THE SUN?

Balloons

HOW DO WE STUDY THE SUN?

HOW ARE SOLAR HIGH-ENERGY RAY TELESCOPES BUILT?

Rotating grids

HOW ARE SOLAR HIGH-ENERGY RAY TELESCOPES BUILT?

Collimators

HOW ARE SOLAR HIGH-ENERGY RAY TELESCOPES BUILT?

Uniformly redundant array (URA) mask

TECHNIQUES

MoirÈ Pattern

Top View

IMAGER TYPES FOR DIFFERENT MISSIONS

GERMANIUM DETECTORS

Why germanium?

Conducts better than silicon when cooled to cryogenic temperatures

REFERENCES R. P. Lin, “Particle acceleration in solar flares and coronal mass

ejections,” IAU Symposium, 195, 15 (2000). Temmer,M., Veronig,A.M., Kontar,E.P., Krucker,S., Vrsnak,B. 2010, The

Astrophysical Journal, 712, 1410-1420Combined STEREO/RHESSI study of CME acceleration and particle acceleration in solar flares

Shao,C., & Huang, G. 2009, The Astrophysical Journal, 694, L162-L165Hard-Soft-Hard Flare Spectra and Their Energy Dependence in Spectral Evolution of a Solar Hard X-Ray Flare

Shih,A.Y. 2009, PhD Thesis, Disseration, University of California, BerkeleyGamma-ray observations of solar-flare ion acceleration

Krucker,S., Hurford,G.J., MacKinnon,A.L., Shih,A.Y., and Lin,R.P. 2008, The Astrophysical Journal, 678, L63-L66Coronal gamma-ray bremsstrahlung from solar flare-accelerated electrons

Wikipedia Nasa website