Exotic Nuclei I


Michael Thoennessen FRIB/NSCL Michigan State University What are “exotic nuclei”?

“Nuclei with ratios of number N to proton number Z much larger or much smaller than those of nuclei found in nature.”

McGraw-Hill Concise Encyclopedia of Physics. (2002). Retrieved August 5 2015 from http://encyclopedia2.thefreedictionary.com/Exotic+nuclei

Terminology:  Exotic nuclei?  Rare ?  Radioactive nuclei?  Nuclei/Nuclides/Isotopes Reaching the extremes

neutron-deficient N=Z

proton-rich superheavy nuclides

neutron-rich Nucleus - -

Nucleus: The nucleus is the small, dense region consisting of and at the center of an . Nuclide: A nuclide is an atomic species characterized by the specific constitution of its nucleus, i.e., by its number of protons Z, its number of neutrons N, and its nuclear energy state. Isotopes: Different nuclides having the same are called isotopes.

A species of identical as regards atomic number (proton number) and number ( number) should be indicated by the word ‘nuclide’, not by the word ‘isotope’.

https://en.wikipedia.org/wiki/Nuclide E.R. Cohen and P. Giacomo, Document I.U.P.A.P.-25 (SUNAMCO 87-1) Origin of the term isotope http://blogs.nature.com/thescepticalchymist/2013/11/isotope-day.html

B. F. Thornton and Shawn C. Burdette, Nature Chemistry 5 (2013) 979 December 4: Isotope Day

http://www.gla.ac.uk/hunterian/visit/events/headline_296351_en.html December 4: Isotope day ..nothing to do with… Different types of nuclides?

Stable: Nuclides which do not decay 128 24 (What about Te: T1/2 = 2.2∙10 years)

Radioactive: Nuclides which decay with a half-life longer than about 10-12s (8Be is unstable: -17 T1/2 = 82 as (8.2∙10 s)

Bound: With respect to neutron or A = 21 isobars

radioactive/ unstable unbound stable Decay of proton-rich nuclei

Unbound nuclides can still be radioactive:

121 Pr: T1/2 = 12 ms (proton emitter)

Unbound nuclides do not have to decay by proton emission:

135 Tb: T1/2 = 1 ms + Sp = –1.19 MeV - β emitter Coulomb/angular momentum barrier

proton unbound proton radioactive

neutron unbound Exotic proton-rich nuclides

Nuclides with a very large proton access: Z/N = 1

Ratio: Z/N = 2 Z/N = ∞ : 1H Z/N = 2 : 3He,9C Difference: Z–N = 8 : 48Ni Z/N = ∞ Unbound proton-rich exotic nuclides

Z/N = 1

Z/N = 2 Z/N = 3 : 4Li,8C Z/N = 3

Z/N = ∞ Great tool: LISE++

http://lise.nscl.msu.edu First stop for information: NNDC/AME

www.nndc.bnl.gov Evaluation: AME

Only as a first step:

Always check the original literature!

https://www-nds.iaea.org/amdc/ http://amdc.impcas.ac.cn/ Discoveries are driven by new technologies

Fusion evaporation Projectile WWII Reactors fragmentation First accelerators

Mass spectroscopy

Radio- activity

M. T. and B.M. Sherrill, Nature 473 (2011) 25 http://www.nscl.msu.edu/~thoennes/isotopesTimeline Movie First new isotope produced with an accelerator

7Li + p 8Be 2α

J.D. Cockcroft and E.T.S. Walton, Nature 129 (1932) 649 Proton-unbound nuclei

9B: First proton unbound isotope (1940)


6Be, 7B, and 8C: 2,3, and 4-proton unbound isotopes

R.O. Haxby et al., Phys. Rev. 58 (1940) 1035 1957: Two-proton unbound nucleus: 6Be


G.F. Bogdanov et al., J. Nucl. Ener. 8 (1958) 148 1967: Three-proton unbound nucleus: 7B


R.L. McGrath et al., Phys. Rev. Lett. 19 (1967) 1442 1974: Four-proton unbound nucleus: 9C


R.G.H. Robertson et al., Phys. Rev. Lett. 32 (1974) 1207 1963: Beta-delayed protons


R. Barton et al., Can. J. Phys. 31 (1963) 2007 Fusion evaporation reactions

M. Thoennessen, Rep. Prog. Phys. 67 (2004) 1187 Fusion-evaporation

Phys. Rev. 80 (1950) 486

Phys. Rev. 81 (1951) 154

238U(12C,4n)246Cf 1970: Proton radioactivity



K.P. Jackson et al., Phys. Lett. 33B (1970) 281 J. Cerny et al., Phys. Lett. 33B (1970) 284 Projectile fragmentation

Fragments were detected in a zero-degree magnetic spectrometer and identified in a ΔE-E silicon detector telescope

Phys. Rev. Lett. 42 (1979) 40 Projectile fragmentation at the proton dripline

M. Langevin et al., Nucl. Phys. A455 (1986) 149 1982: Ground-state proton radioactivity


S. Hofmann et al., Z. Phys. A 305 (1982) 111 2002: Two-proton radioactivity

600 MeV/A 58Ni fragmentation

12 events

75 MeV/A 58Ni fragmentation

M. Pfuetzner et al., Eur. Phys. J. A 14 (2002) 279 J. Giovinazzo et al., Phys. Rev. Lett. 89 (2002) 102501 Mapping the proton dripline: Z<13

I. Mukha et al., Phys. Rev. Lett. 99 (2007) 182501 V.Z. Goldberg et al., Phys. Lett. B692 (2010) 307 12


Mukha et al. EXON 2014 30Ar

C.L. Woods et al., Nucl. Phys. A484 (1988) 145 30

J.C. Batchelder et al., Phys. Rev C 48 (1993) 2593

A.M. Rogers et al., Phys. Rev. Lett. 106 (2011) 252503


H. Suzuki et al., Nucl. Instrum. Meth. B 317 (2013) 756 A.A. Ciemny et al., Phys. Rev. C 92 (2015) 014622 43

96In 94Cd 92Ag Lubos et al. 90Pd PROCON2015

C.B. Hinke et al., Nature 486 (2012) 341 H. Suzuki et al., Nucl. Instrum. Meth. B 317 (2013) 756 K. Rykaczewski et al., Phys. Rev. C 52 (1995) 2310(R) 51

Odd-Z: Still unknown isotopes between proton and β+ emitters Published only in a conference proceeding

Even-Z: A few bound isotopes are still unknown Issue with conference proceedings

NCSR Demokritos, Athens, Greece

MSU A1200 fragment separator 83

Presented at ARIS 2014

Potential 4p emitter

222U was discovered with the reaction 191 Rn 186W(40Ar,4n) so 220U should be accessible with 184W(40Ar,4n).

R. Hingmann et al., Z. Phys. A 313 (1983) 141 Y. Wakabayashi et al., ARIS-2014, PS1-B037 (2014) L. Ma et al., Phys. Rev. C 91 (2015) 051302(R) H.M. Devaraja et al., Phys. Lett. B 748 (2015) 199 Four-proton radioactivity

M. Thoennessen, Rep. Prog. Phys. 67 (2004) 1187 92


223Am 229Am


H.M. Devaraja et al., Phys. Lett. B 748 (2015) 199 Z>102

Utyonkov et al. at EXON-2014



En'yo et al. at EXON-2014

H.M. Devaraja et al., Phys. Lett. B 748 (2015) 199 At and beyond the proton dripline


M. Thoennessen, Rep. Prog. Phys. 67 (2004) 1187 Summary and outlook

 About 1300 proton-rich isotopes have been discovered, most of them by and fusion-evaporation reactions  There are still hundreds of proton-rich isotopes left to be discovered  Both, fusion evaporation and projectile fragmentation continue to be the dominant (only?) production mechanism  Publish the results in the refereed literature!