New approaches to the study of the nucleus

Juha Äystö

New approaches to the study of the nucleus

Juha Äystö

Thanks to H. Fynbo, K. Jungmann, P. Kienle, K.-H. Langanke, M. Lindroos, T. Nilsson, K. Riisager,…

Muons , pbars& Exotic nuclei

Muons , pbars& Exotic nuclei

PHYSICS ISSUES ?

stable+ decay- decay decayp decayspontaneous fission

Explaining complex nuclei from basic constituents Effective nuclear force – Origin of pairing interaction Magic nuclei and shell structure far from stability

The size of the nucleus: halos and skins

Limits of nuclear existence and its implications The end of Mendeleev’s table: superheavy elements Understanding the origin of elements Testing the Standard Model Applications in materials and life sciences

Example: neutron-rich Zr isotopesExample: neutron-rich Zr isotopes

Spectroscopic studies: Beta decay experiments on 97Zr, 99Zr, 103ZrPrompt ff – ray coincidence experiments on

99Zr: W. Urban et al., Eur. Phys. J. A16(2003)1198,99Zr: Nucl. Phys. A689(2001)605100Zr. C.Y. Wu et al., Phys. Lett. B541(2002)59

Collinear laser spectroscopy 96-102Zr: P. Campbell et al., Phys. Rev. Lett. 89(2002)082501

Direct mass measurements with a Penning trap96-104 Zr: S. Rinta-Antila et al., Phys. Rev. C, in press

Spectroscopic studies: Beta decay experiments on 97Zr, 99Zr, 103ZrPrompt ff – ray coincidence experiments on

99Zr: W. Urban et al., Eur. Phys. J. A16(2003)1198,99Zr: Nucl. Phys. A689(2001)605100Zr. C.Y. Wu et al., Phys. Lett. B541(2002)59

Collinear laser spectroscopy 96-102Zr: P. Campbell et al., Phys. Rev. Lett. 89(2002)082501

Direct mass measurements with a Penning trap96-104 Zr: S. Rinta-Antila et al., Phys. Rev. C, in press

”Ground state changes from spherical to deformed via coexistence”

”Ground state changes from spherical to deformed via coexistence”

86 88 90 92 94 96 98 100 102 104

18,5

19,0

19,5

20,0

20,5

21,0

2=0.5

2=0.4

2=0.3

2=0.1

2=0.2

2=0.0

<r2>

(fm

2)

Mass number

P. Campbell, et al.Phys. Rev. Lett. 89(2002)082501

S. Rinta-Antila et al., et al.Phys. Rev. C, in press

Charge radii Two-neutron binding energies

30 40 50 60 70 80 90 100neutron num ber N

-5

0

5

10

15

20

Sn

(MeV

)

neutron drip

valley of stability

add 37 neutrons

experiments

Drip line???

90 95 100 105 110 1151E-5

1E-4

1E-3

0,01

0,1

1

10

100

1E-5

1E-4

1E-3

0,01

0,1

1

10

100

cro

ss s

ect

ion

in

mb

Mass number

Zr from fission

unknownknown

For most exotic species we need more sensitive methods:

ion by ion experimentsnew probes: muons, antiprotons,...

Standard probes of nuclei

Mass, size and electromagnetic momentsRadioactive decaysNuclear reactions

elastic scatteringCoulomb excitationFusionTransfer

Electron scattering

Interaction cross sections < 1 mbarn !

Standard probes of nuclei

Mass, size and electromagnetic momentsRadioactive decaysNuclear reactions

elastic scatteringCoulomb excitationFusionTransfer

Electron scattering

Interaction cross sections < 1 mbarn !

Muons (- ) and radioactive atoms/ions

Formation of - atoms (free ~ 2.2 s)

Slowing down in matter (~ ns)

Atomic capture in high-l state (n~14)

Bohr radius ~ n2/(Zm)Binding energy ~ (Z2m)/n2

Cascade down to n=1=muonic 1s orbit (<< ns)

Auger electronsmuonic X-rays (keV MeV)

Large cross section (~ 10-16 cm2 ~ 108 b !!!)

Muonic atom X-ray spectroscopy

nuclear rms charge radii (charge moments)

accuracy a few am

with e-scattering + optical isotope shift data

accuracy 1 am (<10-3)

nuclear polarization effects

Physics to be extracted

Isotone shifts vs. isotope shifts

nuclear structure far from stability

Isobar charge distributions

charge breaking asymmetry in mirror states

Ground state parameters of Fr, Ra isotopes

P&T violation in atoms

C.Piller et al., Phys. Rev. C 42 (90)182

Nuclear muon capture• follows naturally muonic atom formation

• “inverse - decay”

• capture rates can tell something about nuclear structure E. Kolbe et al., Eur. Phys. J. A 11 (2001) 39

• produces exotic nuclei at high excitation energy structure up to several 10 MeV• several multipoles excited medium spin states• renormalization of gA in nuclear medium

• Nuclear astrophysics, scattering (supernova), post-processing, …• Neutrino physics

-

N

Z-

N

Z

XX A

ZAZ 1

Probability of nuclear - capture ?

Capture lifetime (48Ca) ~ 0.6 s nuclear capture dominates over free muon decay e- +e +

For Sn ~ 0.09 s and for Pb ~ 0.07 s !

~0

78Ni0.2 s

78Cu0.34 s

78Zn1.5 s

78Ga5.5 s

78Ge88 m

78As1.5 h

78Se

N=50

Z=28

1

102

104

An example: - + 78Cu 78Ni* +

B

U

particles: at nearly rest in space at relativistic energies

Merging beams in Storage rings

0 0.5 1 cm

STORAGE DEVICES STORAGE DEVICES

Low-Z Solid / Liquid catcherat K temperatures

Penning or Paul traps

Estimates for muonic atom production rates:

based on 108 /s (low energy) on 108 atoms/cm2

• nested ion & muon trap: rate 10 /s

• solid hydrogen: rate 1 /s (P. Strasser & K. Nagamine)

• superfluid helium: rate similar to solid H or better?

control of the movement of ions/muons by E fields thin surface layer / high packing density(see poster of P. Dendooven)

0

50

100

150

200

0 20 40 60 80 100 120 140 160 180 200

E(keV)

Coun

ts

In-trap spectroscopy

Annular -detector

-detector

-detector

CE- detector

Ion cloud

CP detector

Ions in

118mIn

CE-decay at REXTRAP

L. Weissman, F. Ames, J. Äystö, O. Forstner, K. Reisinger and S. Rinta-Antila,Nuclear Instruments and Methods A 492 (2002) 451

Antiprotonic radioactive atomsProcess Observable Deduced

quantityPhysics

Capture in high orbit (atomic x-sections), cascade

Antiprotonic x-rays O(MeV)

Annihilation orbit, energy shifts

Matter distributions, neutron vs. protons on nuclear surface, …Annihilation (n>7) on

peripheral nucleonDe-excitation , particles, daughter activity

n vs. p annihilation

VOLUME 87, NUMBER 8 P H Y S I C A L R E V I E W L E T T E R S 20 AUGUST 2001

Neutron Density Distributions Deduced from Antiprotonic Atoms

A. Trzcin´ska, J. Jastrze ¸bski, and P. Lubin´skiHeavy Ion Laboratory, Warsaw University, PL-02-093 Warsaw, Poland

F. J. Hartmann, R. Schmidt, and T. von EgidyPhysik-Department, Technische Universität München, D-85747 Garching, Germany

B. KlosPhysics Department, Silesian University, PL-40-007 Katowice, Poland

(Received 28 March 2001; published 2 August 2001)

Collider Technique

• Production of neutron rich nuclei: Fragmentation at medium energies or ISOL method + post acceleration

• Storing of products in a cooler ring• Production of antiprotons with 20-30 GeV protons

(site dependence?)• Cooling and storing of antiprotons • Transfer in collider rings

(Paul Kienle, GSI Future workshop, Oct. 2003)

• Antiproton-Ion-Collider is proposed to measure– total/partial cross sections of antiproton

absorption by RI nuclei

– rms radii of n-p and their differences

Antiproton Absorption

• Yields of A-1 isobars with (N-1) or (Z-1)

• Absorption proportional to <r²> of neutrons or protons

• Exclusive recoil spectroscopy

Luminosity )/1()/( FClNfNL

pII

santiprotonofnumber

ionstheoffrequencygcirculatin

ionsofnumber

p

I

I

N

f

N

EXAMPLE1.5 ,cm 100 )/1( ,10)/(

,10 ,s 10 x 2 ,10For

2-1

9-166

FCl

NfNpII

2241 105.1045.0

rateReaction

cmforsLR RR

factor Lorentz

area ninteractio of inverse

factor ncecircumfere

tolengthintractionofratio

)/1(

)/(

F

Cl

1222103 scmL

Unbunched beams

ConclusionsConclusions

Muons and antiprotons offer an attractive method for high-sensitivity measurements on exotic nuclei

Charge and mass distributions obtained viaatomic X-raysabsorption experiments

Excited states probed via unique muon capture process

Request for muons and antiprotons

thermal muon source of ~108 muons/santiproton storage ring with ~109 p/s

Two RAMA workshops organized in 2001 @ CERN and TrentoFuture: Working group should be set up in connection with SPL study