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