theresa brandt 2 june 2007 cream: improving our understanding of cosmic rays great lakes cosmology...
TRANSCRIPT
Theresa Brandt2 June 2007
CREAM: Improving Our Understanding of Cosmic Rays
Great Lakes Cosmology Workshop 8
CREAM I, AntarcticaCREAM Collaboration
Power law in energy:
Change in spectral slope: “Knee” at ~1015 eV From ≈ 2.7 to 3.0
Due to change in acceleration mechanism?
What about propagation conditions?
Gather clues from composition
and primary to secondary ratios.
All-particle CR Spectrum
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dN
dE∝ E−α
S. Swordy
... 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 SNRChandra Telescope
CR Origins: Supernova
Transport Equation:Transport Equation:
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∂Ni
∂E=Qi(E,x,t)+∇⋅Di∇Ni( )−∇⋅uNi−
∂∂E
bi(E)Ni(E)[ ]−piNi+vρm
dσ i,k(E, ′ E )dE∫ Nk( ′ E )
k≥i
∑ d ′ E
CR Propagation
M, S, & M, Prop.
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
4 main subsystems:➢ TCD (Z), TRD (E), SCD (Z), Cal (E)Timing Charge Detector, Transition Radiation Detector,
Silicon Charge Detector, and Calorimeter
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)CREAM
Particle DetectorCharge and Energy:
➢+1 ≤ Z ≤ 26➢1012 eV <~ E <~1015 eV
QuickTime™ and aYUV420 codec decompressor
are needed to see this picture.
CREAM, AntarcticaCREAM Collaboration
NASA/CSBF
HEAO
CRN
CREAM TRD
CREAM Cherenkov
PreliminaryPreliminary
S. Swordy, S. Wakely
Total Particle Energy (eV)
Flu
x (m
2 s
sr G
eV)-1 HEAO
CRN
Oxygen Spectrum
HEAO
CRN
S. Swordy, S. Wakely
CREAM TRDCREAM Cherenkov
PreliminaryPreliminary
HEAO
CRN
Total Particle Energy (eV)
Flu
x (m
2 s
sr G
eV)-1
Carbon Spectrum
The CREAM Collaboration: University of MarylandH. 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 ChicagoP. Boyle, S. Swordy, S. Wakely
Penn State UniversityN. B. Conklin, S. Coutu, S. I. Mognet
Ohio State UniversityP. Allison, J. J. Beatty, T. J. Brandt
University of MinnesotaJ. T. Childers, M. A. DuVernois
University of Sienna & INFN, ItalyM. G. Bagliesi, G. Bigongiari, P. Maestro,
P. S. Marrocchesi, R. ZeiEhwa Womans University, S. Korea
H. J. Hyun, J. A. Jeon, J. K. Lee, S. W. Nam, I. H. Park, N. H. Park, J. YangNorthern Kentucky University
S. NutterKent State University
S. MinnickGoddard Space Flight Center
L. BarbierKyungpook National University, S. Korea
H. ParkLaboratoire 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, FranceR. Bazer-Bach, J.N. Perie
Universitad Nacional Auto´noma de Mexico, MexicoA. Menchaca-Rocha
CREAM III assemblyCREAM Collaboration
HEAO (90)
Simon (80)
Lezniak (78)
Juliusson (74)
Caldwell (77)
Orth (78)
Swordy (90)
Dwyer (87)
Mahel (77)
Castellina & Donato
Top bottom:=0.3, 0.46, 0.6, 0.7, 0.8
➢Secondary flux reflects propagation conditions for a given source spectrum. ➢Ratios of s:p at given E reduces source dependence.➢Assume ~ steady state.
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Ns=Qsτ esc=βc ρ
mσ p→sNp
H2
D ⎛ ⎝ ⎜
⎞ ⎠ ⎟ ⇒ Ns
Np
∝ 1D
~ E−δ
Carbon as primary:➢common stellar process end-product
Boron as secondary:➢stable, rarely stellar-synthesized ➢BBN abundence is rel. well known.➢want properties like selected primary's.
All-particle spectral index goes as the source and propagation energy indices:
➢ ➢2.7 = 1.1+1+0.6
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=γ+1+δ
B:C