CREAM: Improving Our Understanding
of Cosmic Rays
Great Lakes
Cosmology
Workshop 8
Theresa Brandt
2 June 2007
CREAM I, Antarctica
CREAM Collaboration
All-particle CR Spectrum
Power law in energy:
dN
 E 
dE
Change in spectral slope:
 “Knee” at ~1015 eV
 From  ≈ 2.7 to 3.0

Due to change in acceleration
mechanism?
What about propagation
conditions?
S. Swordy
Gather clues from composition
and primary to secondary ratios.
CR Origins: Supernova
... are good candidates because
they are point-like, stellar objects,
as required by abundances.
➢
SN shock lifetime implies
Emax
~ Z x 1014 eV, which is a potential
source of the knee.
➢
typical SN luminosity at a few %
efficiency could supply observed CRs.
➢
multi-wavelength observations
imply this efficient acceleration.
➢
Kepler's SNR
Chandra Telescope
CR Propagation
M, S, & M, Prop.
Transport Equation:
d i,k(E,E)
Ni
v

Q (E,x,t)DiNiuNi  bi(E)Ni(E)piNi   
Nk(E)dE
E i
E
m ki
dE
CREAM Science Goals

Determine elemental
composition from
1012 up to 1015 eV

Measure secondary to
primary ratio (e.g. B/C)

Observe predicted “knee”
in proton spectrum
CREAM I Hang Test,
Antarctica
CREAM Collaboration
Cosmic Ray Energetics and Mass
Particle Detector
Charge and Energy:
➢+1 ≤ Z ≤ 26
12 eV <~ E <~1015 eV
➢10
➢
4 main subsystems:
TCD (Z), TRD (E), SCD (Z), Cal (E)
Timing Charge Detector, Transition Radiation Detector,
Silicon Charge Detector, and Calorimeter
➢
CREAM
➢
Flown on a Long-Duration Balloon
over Antarctica
CREAM I: 42 day (16 Dec 04 - 27 Jan 05)
CREAM II: 28 day (16 Dec 05 - 13 Jan 06)
QuickTime™ and a
YUV420 codec decompressor
are needed to see this picture.
CREAM, Antarctica
CREAM Collaboration
NASA/CSBF
Oxygen Spectrum
Flux (m2 s sr GeV)-1
Preliminary
HEAO
CRN
CREAM Cherenkov
CREAM TRD
Total Particle Energy (eV)
S. Swordy, S. Wakely
Carbon Spectrum
Flux (m2 s sr GeV)-1
Preliminary
HEAO
CRN
CREAM Cherenkov
CREAM TRD
Total Particle Energy (eV)
S. Swordy, S. Wakely
The CREAM Collaboration:
University of Maryland
H. S. Ahn, O. Ganel, J.H. Han, K.C. Kim, M. H. Lee, L. Lutz, A. Malinine,
E. S. Seo, R. Sina, P. Walpole, J. Wu, Y. S. Yoon, S. Y. Zinn
University of Chicago
P. Boyle, S. Swordy, S. Wakely
Penn State University
N. B. Conklin, S. Coutu, S. I. Mognet
Ohio State University
P. Allison, J. J. Beatty, T. J. Brandt
University of Minnesota
J. T. Childers, M. A. DuVernois
University of Sienna & INFN, Italy
M. G. Bagliesi, G. Bigongiari, P. Maestro,
P. S. Marrocchesi, R. Zei
Ehwa Womans University, S. Korea
H. J. Hyun, J. A. Jeon, J. K. Lee, S. W. Nam,
I. H. Park, N. H. Park, J. Yang
Northern Kentucky University
S. Nutter
Kent State University
S. Minnick
Goddard Space Flight Center
L. Barbier
Kyungpook National University, S. Korea
H. Park
Laboratoire de Physique Subatomique et de Cosmologie,Grenoble, France
M. Mangin-Brinet, A. Barrau, O. Bourrion, J. Bouvier, B. Boyer, M. Buenerd, L. Eraud, R. Foglio, L.
Gallin-Martel, Y. Sallaz-Damaz, J. P. Scordilis
Centre d’Etude Spatiale des Rayonnements, Toulouse, France
R. Bazer-Bach, J.N. Perie
CREAM III assembly
Universitad Nacional Auto´noma de Mexico, Mexico
CREAM Collaboration
A. Menchaca-Rocha
Castellina & Donato
B:C
Secondary flux reflects
propagation conditions
for a given source
spectrum.
➢Ratios of s:p at given
E reduces source
dependence.
➢Assume ~ steady state.
➢
HEAO (90)
Simon (80)
Mahel (77)
Lezniak (78)
Juliusson (74)
Caldwell (77)
Orth (78)
Swordy (90)
Top  bottom:
=0.3, 0.46, 0.6, 0.7, 0.8
Dwyer (87)
c 
H 2 
N
NsQs esc 
 ps N p    s  1 ~ E 
Np D
m
 D 
Carbon as primary:
All-particle spectral index goes
➢common stellar process end-product
as the source and propagation
Boron as secondary:
energy indices:
➢stable, rarely 
stellar-synthesized
➢   1
➢BBN abundence is rel. well known.
➢2.7 = 1.1+1+0.6
➢want properties like selected primary's.