introduction to experimental nuclear astrophysics 한인식이화여자대학교 2007 년 2 월...
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Introduction to Introduction to Experimental Nuclear Experimental Nuclear
AstrophysicsAstrophysics
한인식한인식
이화여자대학교이화여자대학교
20072007 년 년 22 월 월 26-2826-28 일일APCTP Workshop @ APCTP Workshop @ 포항포항
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OutlineOutline
IntroductionIntroduction– Nuclear AstrophysicsNuclear Astrophysics– Experimental considerationsExperimental considerations
Selective experimentsSelective experiments– Nuclear reactions in the SunNuclear reactions in the Sun– Neutrinos from the SunNeutrinos from the Sun
Explosive environmentExplosive environment– Nuclear reactions in supernovaeNuclear reactions in supernovae– Nu-SNS ProjectNu-SNS Project
ConclusionsConclusions
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Diff = 107
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Some of the most compelling questions in Some of the most compelling questions in naturenature How were the elements from iron to uranium How were the elements from iron to uranium
made?made? How does the sun shine for so many years?How does the sun shine for so many years? What is the total density of matter in the What is the total density of matter in the
universe?universe? How did the stars, galaxies evolve?How did the stars, galaxies evolve?
Require a considerable amount of nuclear Require a considerable amount of nuclear physics information as inputphysics information as input
Nuclear AstrophysicsNuclear Astrophysics
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decay - Be HeHe
Bang Big - Li He,He, H, 844
34
< Hoyle in 1953 >
C α 3 12 Is insufficient to explain the observed abundance
γ C α Be 128
Proposed O+ at 7.68 MeV in 1953
438.42 α Be8
C12
MeV 367.7
Measured at 7.65 MeV in 1957
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“ It is a remarkable fact that humans, on the basis of experiments and measurements carried out in the lab, are able to understand the universe in the early stages of its evolution, even during the first three minutes of its existence.” Fowler (Nobel prize 1983)
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8
2028
50
82
126
8
20
28
50
82
Stable
Observed Unstable
Big Bang
Stellarevolution
rp process
s process
r process
Nucleosynthesis in Cosmos Nucleosynthesis in Cosmos 2,771293 NNDC (BNL, 2000)3,064
Nuclear reactions in stars
produce energy
generate the elements
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keVTkTE
MeVfmR
ZZ
R
eZZE
T
B
1062.8
)(
44.1
8
212
21
Nucleosynthetic reactions are typically dominated by Coulomb barriers
8
3
17 18
14 18
10
d + p He +
F + p Ne +
O + Ne +
T K
T
B
B
B
E 10 keV
E 400 keV
E 2.52 MeV
E 4.00 MeV
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Thermonuclear reactions in stars
21 2
0
-1/21/20
1/2
-1/23/ 2 0
2 Z ZS(E) (E)E exp
λ (E) (E) (E)dE
S(E) 2E 2 E E dE exp(-bE ) exp
E kT kT (kTE)
8 1 S(E) E exp bE dE
E kTkT
e
Gamow peak
tunnelling throughCoulomb barrier exp(- )
Maxwell-Boltzmanndistribution exp(-E/kT)
rela
tive p
robabili
ty
energykT E0
E/EG
E0
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SOHO, 171A Fe emission line
Nuclear Reactions in the SunNuclear Reactions in the Sun
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PP-I
Qeff= 26.20 MeV
proton-proton chain
p + p d + e+ + p + d 3He +
3He + 3He 4He + 2p
86% 14%
3He + 4He 7Be +
2 4He
7Be + e- 7Li + 7Li + p 2 4He
7Be + p 8B + 8B 8Be + e+ +
99.7% 0.3%
PP-II
Qeff= 25.66 MeV PP-III
Qeff= 19.17 MeV
net result: 4p 4He + 2e+ + 2 + Qeff
proton-proton chain
From M. Aliotta
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From P. Parker @ Yale Univ.
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From P. Parker @ Yale Univ.
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First experimental detection of solar neutrinos:
• 1964 John Bahcall and Ray Davis have the idea to detect solar neutrinos using the reaction:
eArCl e3737
• 1967 Homestake experiment starts taking data
• 100,000 Gallons of cleaning fluid in a tank 4850 feet underground
• 37Ar extracted chemically every few months (single atoms !) and decay counted in counting station (35 days half-life)
• event rate: ~1 neutrino capture per day !
• 1968 First results: only 34% of predicted neutrino flux !
solar neutrino problem is born - for next 20 years no other detector !
Neutrino production in solar core ~ T25
nuclear energy source of sun directly and unambiguously confirmed
solar models precise enough so that deficit points to serious problem
From Schatz@MSU
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12
14
16
18
20
22
24
26
28
30
32
Gialanella
D&B-fits
Typel-fits
Baby (Typ)
Baby (D&B)
GSI-IIJunghans
Strieder
Trache
Azhari
Hammache
Davids
Iwasa
Kikuchi
Hammache
Liu
Motobayashi
Filippone
Vaughn
Kavanagh
Parker
direct methodcoulomb breakupANC methodNaBoNA
S 17(0
) [e
V-b
]DirectCoulomb dissociationANCNaBoNA (Napoli Bochum Nuclear Astrophysics)
From L. Gialanella @ INFN
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Art Champagne for ENAM04
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Art Champagne for ENAM04
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Solar Neutrino Problem
p + p 2H + e+ + e p + e- + p 2H + e
2H + p 3He +
3He + 3He 4He + 2p 3He + p + e+ +e
3He + 7Be +
7Be + e- 7Li + +e7Be + p 8B +
7Be + p + 8B + 2 + e
SOLAR NEUTRINO PROBLEMeither
Solar Models are Incomplete/incorrector
Neutrinos undergo flavor changing oscillation
Gallium flux = 57% SSMChlorine flux = 34% SSMSuper-K flux = 47% SSM
EXPERIMENTAL RESULTS
FUSION REACTIONS
From P. Doe, J. Wilkerson, H. Rebertson
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Sudbury Neutrino Observatory
1700 tonnes Inner Shielding H2O
1000 tonnes D2O
5300 tonnes Outer Shield H2O
12 m Diameter Acrylic Vessel
Support Structure for 9500 PMTs, 60% coverage
Urylon Liner and Radon Seal
From P. Doe, J. Wilkerson, H. Rebertson
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The SNO Detector during Construction
From P. Doe, J. Wilkerson, H. Rebertson
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Comparison of resultsComparison of results
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The Nobel Prize in Physics 2002
"for pioneering contributions to astrophysics, in particular for the detection of cosmic neutrinos"
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Astrophysically Important Nuclear Astrophysically Important Nuclear ReactionsReactions
77Be(p,Be(p,))88BB88Li(Li(,n),n)1111BB1212C(C(,,))1616OO1414O(O(,p),p)1717FF
1515O(O(,,))1919NeNe17,1817,18F(p,F(p,))14,1514,15OO
2525Al(p,Al(p,))2626SiSi4444Ti(Ti(,p),p)4747VV
5656Ni(p,Ni(p,))5757CuCu8585Kr(n,Kr(n,))8686KrKr
134134Cs(n,Cs(n,))135135CsCs……
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Nuclear reactions in stars
produce energy
generate the elements
Experimental Nuclear Astrophysics
Lab studies of reaction cross-sections
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A Better Set of Models for Explosive Events
Hydrodynamic Properties
Temperature
Density
Flow
Etc.
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Requires a Better Understanding of Nuclear Processes
Unstable Isotopes Reaction rates Excited states Decay rates
Bounds of Stability Proton drip-line Neutron drip-line
Understanding Nucleosynthesis & Energy Generation in Explosive Events
To study unstable isotopes we need radioactive beams!
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Supernova Simulations First 300 ms: A. Burrows
300 km10 km
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t = 0 Neutrino-driven wind forms right after SN core collapse. n + p n +
t = 18 ms Seeds form. Exotic neutron-rich 78Ni
t = 568 ms – 1 s Heavy r-elements synthesize.
SUPERNOVA R-PROCESS
Otsuki, Tagoshi, Kajino & Wanajo 2000, ApJ 533, 424 Wanajo, Kajino, Mathews & Otsuki 2001, ApJ 554, 578
t = 0
Fe
○
Fe
○
Pb○
Pb208○
Pb○
Fe56
○
Ni78
N
Z
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M.S. Smith and K.E. Rehm,Ann. Rev. Nucl. Part. Sci, 51 (2001)
In many cosmic phenomena, radioactive nuclei play an influential In many cosmic phenomena, radioactive nuclei play an influential
role, hence the need for role, hence the need for Radioactive Ion Beams
2,771293 NNDC (BNL, 2000)3,064
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X-ray burst and novaeX-ray burst and novae
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25Al
24Mg
23Na
22Ne21Ne20Ne
22Na
23Mg
24Al
21Na
22Mg
19F
18O
21Mg
20Na
19Ne
18F
17O
18Ne
17F
16O
15N
15O14O
13N
12C 13C
14N
p
HCNO cycle
CNO cycle
Stable
Unstable
Z
Nrp process
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MeasurementsMeasurements
Direct measurements are desirable ways to Direct measurements are desirable ways to measure the measure the 1515O(O(,,))1919Ne and Ne and 1414O(O(,p),p)1717F F reactions over indirect methods.reactions over indirect methods.
Only became possible after new generation Only became possible after new generation of accelerators that can make of accelerators that can make 14,1514,15O and O and 1717F F beams in the late 90’s.beams in the late 90’s.
There are still large uncertainties of the There are still large uncertainties of the reaction relevant to X-ray burst and novae. reaction relevant to X-ray burst and novae.
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OO
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OUTLOOKOUTLOOK Measurements using radioactive Measurements using radioactive
beams have given us a deeper beams have given us a deeper understandingunderstanding Big Bang, the sun, novae, supernovaeBig Bang, the sun, novae, supernovae More intense radioactive beams @ RIKEN, More intense radioactive beams @ RIKEN,
MSU, ANL, ORNL, RIA(future)MSU, ANL, ORNL, RIA(future) We expect to obtainWe expect to obtain more more
experimental results of the important experimental results of the important reactions that are relevant to both reactions that are relevant to both interesting stellar sites and big bang interesting stellar sites and big bang nucleosynthesis in the future.nucleosynthesis in the future.
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U H M
E P
The Nu-SNS Project
Ed HungerfordUniversity of Houston
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SNS is the world’s brightest intermediate energy pulsed
neutrino source
Nuclear Reactors SNS Particle Accelerators
Energy
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Right energy rangeSupernova neutrino spectra, 100 ms post-bounce
0
0.005
0.01
0.015
0.02
0.025
0.03
0.035
0.04
0 3 6 9 12 15 18 21 24 27 30 33 36 39 42 45 48 51
Energy, MeV
Ne
utr
ino
Flu
x
e
0
0.005
0.01
0.015
0.02
0.025
0.03
0.035
0.04
0 3 6 9 12 15 18 21 24 27 30 33 36 39 42 45 48 51
Energy, MeV
Ne
utr
ino
Flu
x
e
SNS neutrino spectra
• spectra from the SNS are JUST RIGHT, having significant overlap with the spectra of neutrinos generated in a supernova explosion!
This gives us a unique opportunity to study neutrino interactions relevant to the region of interest for Supernova
• spectra from nuclear reactors are TOO COLD!• spectra from accelerators are TOO HOT!
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U H M
E P The Oak Ridge Spallation
Neutron Source
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U H M
E P SNS Parameters
•Primary proton beam energy - 1.3 GeV
•Intensity - 9.6 1015 protons/sec
•Number of protons on the target 0.687x1016 s-1 (1.1 ma)
•Pulse duration - 380ns(FWHM)
•Repetition rate - 60Hz
•Total power – 1.4 MW
•Liquid Mercury target
• 0.13 neutrinos of each flavor produced by one proton (9 x 1014 s-1)•Number of neutrinos produced ~ 1.91022/year•There is a larger flux of ~MeV anti-neutrinos from radioactive decay from the target
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U H M
E P
Motivation for -SNS
Important Energy Window
•Just right for supernovae studies•SN detector calibration •Almost no data
Extremely high neutrino flux
• Potential for precision measurements• Can address a number of new physics issues• Nuclear Physics processes• Can begin with small detectors
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U H M
E P
18 - Wide Angle Chopper Spectrometer Commission 2007
17 - High Resolution Chopper SpectrometerCommission 2008
Spallation Target
-SNS
Incoming proton beam
18 - Wide Angle Chopper Spectrometer Commission 2007
17 - High Resolution Chopper SpectrometerCommission 2008
Spallation Target
-SNS
Incoming proton beam
The SNS Layout
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U H M
E P
Concluding Remarks
N reactions are important for supernovae Influence core collapse Affect shock dynamics Modify the distribution of A>56 elements Affects r process - nucleosynthesis May be the dominant source of B, F, 138La, 180Ta
N cross sections are interesting nuclear physics Sensitive to nuclear structure In medium modifications of weak coupling constants
Only + C cross sections have been measured (10%) The SNS provides a unique opportunity to measure
N cross sections at energies most relevant for supernovae and nuclear structure
Cross section measurements on 2 targets to < 10% accuracy in 1 year!
We have a strong collaboration of experimentalists and theorists: -SNS
Modest cost ~$10M Proposal submitted DOE in early August of 2005 3 yrs required for construction (FY09-FY11) Operations could begin by FY12
감사합니다.
Thank you for y
our atte
ntion!