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

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

Diff = 107

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

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

“ 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)

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

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

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

SOHO, 171A Fe emission line

Nuclear Reactions in the SunNuclear Reactions in the Sun

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

From P. Parker @ Yale Univ.

From P. Parker @ Yale Univ.

http://wwwlapp.in2p3.fr/neutrinos

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

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

Art Champagne for ENAM04

Art Champagne for ENAM04

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

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

The SNO Detector during Construction

From P. Doe, J. Wilkerson, H. Rebertson

Comparison of resultsComparison of results

The Nobel Prize in Physics 2002

"for pioneering contributions to astrophysics, in particular for the detection of cosmic neutrinos"

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……

Nuclear reactions in stars

produce energy

generate the elements

Experimental Nuclear Astrophysics

Lab studies of reaction cross-sections

A Better Set of Models for Explosive Events

Hydrodynamic Properties

Temperature

Density

Flow

Etc.

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!

Supernova Simulations First 300 ms: A. Burrows

300 km10 km

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

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

X-ray burst and novaeX-ray burst and novae

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

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.

OO

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.

U H M

E P

The Nu-SNS Project

Ed HungerfordUniversity of Houston

SNS is the world’s brightest intermediate energy pulsed

neutrino source

Nuclear Reactors SNS Particle Accelerators

Energy

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!

U H M

E P The Oak Ridge Spallation

Neutron Source

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

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

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

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!