Hirschegg 2017 Jan. 18
Neutron star mergers: From gravitational waves to nucleosynthesis

Experimental beta-decay rates
of r-process nuclei
Shunji NISHIMURA
RIKEN Nishina Center

Hirschegg 2017 Jan. 18
Neutron star mergers: From gravitational waves to nucleosynthesis

Experimental beta-decay rates
of r-process nuclei
Shunji NISHIMURA
RIKEN Nishina Center🌟 171 T1/2
(66 new half-lives !)🌟 118 T1/2
(70 new half-lives !)Impact on
formation of rare-earth
peak at freeze-out time

Where is the site of heavy elements ?
(r-Process Nucleosynthesis)
Type II Supernovae

Neutron star merger ?

NASA/JPL-Caltech/O.Krause(Steward observatory)- Mechanism of Explosion.. ?
- Lack of Neutrino, Neutron ：Ye < 0.5?
- Strong magnetic field ?
N. Nishimura, T. Takiwaki, F.-K. Thielemann
Astrophys. J. 810 109 (2015)- Extremely neutron-rich nuclei- Very Rare to have two neutron stars
close together.
- Not possible in 1st stars !?

S. Wanajo

Origin of Heavy Elements
Supernovae vs Neutron Star Merger
r-process conditions:Ye, S, τ, EOS, …

Network calculationwith Nuclear Properties

Supernovae explosion?

J.J.Cowan C.Sneden, Nature 440 (2006)

Neutron star merger?

S. Wanajo

r-process abundance Z, A

Mass … r-proces path (n,γ) ⇄ (γ,n)
Half-lives … process speed/abundance
Delayed neutron emission & Fission… freeze-out path, odd-even
Nuclear Struture- Neutron Magic (N=50, 82, 126) ,Deformation, QuenchingIntroduction: Rapid neutron-capture (r-) process andthe Rare-Earth Element (REE) peak
JAEA: http://asrc.jaea.go.jp/soshiki/gr/chiba_gr/koura/infoKouraDecay_e.html?

Introduction: The formation mechanism of rare-earth peak

Meet
“Kink”

Fissionr-processpathr-process
path

R. Surman et al, PRL 79, 10 (1997)

Solid line: constant Sn
Dashed line: constant T1/2
Ø Interplay of nuclear deformationand β decay
Ø Forms during freeze-out.

The spontaneous and β-delayedﬁssion cycling takes place in thevery heavy region, part offission fragments locates in theregion of rare-earth peak !?

Origin of Rare-Earth Elements
R. Surman’s talk

S. Goriely et al PRL 111, (2013)

C. Sneden et al.(2008)

decay rates, masses, fission, b-delayed neutronß à magic, deformation

Decay Spectroscopy at RIBF

Location of Decay Station at RIBF

84 high-purity Ge crystals in 12 clusters
Resolution : 2.5 keV
Efficiency : 15% @ 662 keV

Decay Exp.

238U

… 345 MeV/u,… Intensity = 5 – 12 pnA (now 30-50pnA)

EURICA Spectrometer at RIBF
Beta-counting system WAS3ABi
inside EURICA

EURICAgamma-ray

Identificationof RI

Primary Beam
(238U / 124Xe / 78Kr)
RI Beam

Production
TargetSeparationof RI

β-decay half-lives of neutron-rich nuclei
Decay experiments (2009, 2012 ~ 2016)

(sec)

103

1

A. Estrade(2016)

F.Recchia(2016)

G. Benzoni et al. PLB 751 (2015)
3 new half-lives
G. Lorusso et al. PRL 115 (2015)
40 new half-lives
Z.Y. Xu et al. PRL 113 (2014)
5 new half-lives
S. Nishimura et al. PRL 106 (2011)18 new half-lives

10-3

β-decay half-lives on r-process path

130Cd

110 half-lives(40 new T1/2)
G. Lorusso

Beta-decay Half-lives N = 82 à Feedback to the Theory

129Ag

132

T1/2 =162ms

125Tc

130Cd

126Ru

131

128Pd

127Rh

130Cd

K.Langanke Phys. Scr. T152 (2013) 014011(Courtesy of G. Martines-Pinedo)

RIBF
EURICA

B.Pfeiffer et al.
(2001)

So call r-process waiting point nuclei (N=82)- r-process path- residual r-matter flow in freeze-out

Shell model ß ~ 25% shorter T1/2
Confirmed by R. Dunlop (2016, TRIUMF)
130Cd … T
1/2 = 126 (4) ms

110 Half-lives of Very Neutron-Rich Rb to Sn
40 new half-lives !

G.Lorusso et al.,PRL 114, 192501 (2015)SN
18 new half-lives ! PRL 106, 052502 (2011)r-process Abundance with New T1/2 (RIBF)
G.Lorusso et al., PRL (2015)

BeforeAfter new RIBF data
1st Peak
2nd Peakr-process AbundanceDip
problem! 128Te130Xe

3rd Peak
195Pt

Rare earth
elem.
232Th

238U

235U

80

100

120

140

Assumption: (n, γ) ⇄ (γ, n) equilibrium.

160

180
200
Mass A

220

240

Universality of r-process elements (Z > 56)

Decay Spectroscopy around mass A =160 was performed !

Survey of Decay Properties at RIBF ( EURICA )half-life（sec）

EURICA Data( 2012 – 2016 )New Isotopes … 7

Delayed γ … 37

Beta-decay half-life … 144Delayed neutron … 5

Isomer … 14

Proton emission … 3825050

440 isotopes
2828

Rare-Earth Peak Formation at Freeze-Out Time
R. Surman et al. PRL 79 (1997)

Test r-Process calculation with new RIBF dataHalf-lives and Mass Measurement
mass (known)

Mass & beta-decay half-lives
M.R.Mumpower, R. Surman et al.
arXiv:1609.09858

(a)

(b)

KTUY-GT2
RHB+pn-RQRPA
FRDM-QRPA

Large
Uncertainty

0.50

Half-life (ms)[MeV] 1.0

Mass Diff. Mi – Mduflo-Zuker

J. Wu: PRL (accepted)-0.5-1.09095100105

110

Neutron number (N)115
Neutron number (N)92 β-Decay Half-lives (Mass A = 144 – 175)
vs FRDM+QRPA
J. Wu, PRL (accepted)
CesiumLanthanum

Praseodymium

Promethium

Sudden reductionof T1/2 at N=96à 97

Barium

CeriumNeodymium

Europium

Terbium

Holmium

N=104 à 105
Samarium

Gadolinium

Dysprosium

Nucleon paring effect92 β-Decay Half-lives (Mass A = 144 – 175)vs KTUY+GT2
J. Wu, PRL (accepted)
CesiumBariumLanthanum

Praseodymium

Promethium

Europium

Terbium

CeriumNeodymiumSamarium

Gadolinium

Dysprosium

Holmium

KTUY+GT2 shows systematic trends similar with exp. values in mid-shell.
However, it can not reproduce even-odd effects.

92 β-Decay Half-lives (Mass A = 144 – 175)
vs RHB+pn-RQRPA
J. Wu, PRL (accepted)
CesiumBariumLanthanum

Praseodymium

Promethium

Europium

Terbium

CeriumNeodymiumSamarium

Gadolinium

Dysprosium

RHB+pn-RQRPA underestimates the T1/2 for Z=55-56 (Cs, Ba) andoverestimates the T1/2 for Z =63-67 (Eu, Gd, Tb, Dy, Ho).
No reproduce of even-odd effects.

Holmium

Discussion: Two significant featuresPreviousmeasurements
Thiswork

A sudden drop of feature at neutron number N=97 and N=105.
( N = 100 : deformed sub-shell gap?)

Rare-Earth Peak Formation

r-Process Elemental Abundance (A = 150-179)

J. Wu et al. PRL (accepted)

Uncertainty of β-decay half-lives à r-Process Rare-Earth PeakExperimental Feedback and Evaluation of the r-Process Rare-Earth Peak Formation

Perspective

(sec)

N=82

N=50

NNDC:
Total Pn …. ~ 150 nuclei + ...
Total P2n … 13 (mainly light RI)

EURICA Collaboration
１９ countries：２３７ collaborators
J. Agramunt, P. Aguilera, T. Alharbi, A. Algora, G. Angelis, N. Aoi, P. Ascher, R. Avigo,
H.Baba, C. Borcea, A. Boso, A.M. Bruce, R.B. Cakirli, F.L.Bello Garrote, G. Benzoni,
J.S.Berryman, R. Berta, B. Blank, N. Blasi, A. Blazhev, P. Boutachkov, S. Bonig, A.
Bracco, F. Browne, F. Camera, R.J. Carroll, S. Ceruti, I. Celikovic, K.Y. Chae, J. Chiba,
L. Coraggio, A. Covello, F.C.L. Crespi, J.-M. Daugaus, R. Daido, P. Davis, M.C.
Delattre, F. Diel, F. Didiejean, Zs. Dombradi, P. Doornenbal, F. Drouet, H.J. Eberth, A.
Estrade, Y. Fang, T. Faestermann, G. France, S. Franchoo, Y. Fujita, N. Fukuda, A.
Gadea, E. Ganioglu, A. Gargano, W. Gelletly, M. Gerbaux, R. Gernhauser, G. Gey, J.
Giovninazzo, S. Go, N. Goel, T. Goigoux, M. Gorska, A. Gottardo, H. Grawe, S. Grevy,
C. Griffin, Vi. Guadilla, T. Hashimoto, S. Hayakawa, J. Henderson, C. Hinke, N.
Hinohara, E. Ideguchi, S. Ilieva, N. Inabe, T. Ishigaki, T. Isobe, Y. Ito, D.G. Jenkins, P.R.
John, H.S. Jung, A. Jungclaus, T. Kajino, D. Kameda, H. Kanaoka, Y. Kanke, Y. Kawada,
G.D. Kim, Y.-K. Kim, G. Kiss, Ka. Kobayashi, K. Kobayashi, M. Kobayashi, N.
Kobayashi, K. Koehler, I. Kojouharov, T. Komatsubara, F.G. Kondev, Z. Korkulu, Y.
Kondo, M. Kowalska, T. Kroll, R. Krucken, T. Kubo, S. Kubono, M. Kurata-Nishimura,
T. Kurtukian Nieto, N. Kurz, I. Kuti, Y.K. Kwon, G.J. Lane, S. Lalkovski, G. Lane, E.
Lee, J. Lee, P. Lee, S. Lenzi, M. Lewitowicz, Z. Li, J. Liu, T. Lokotko, G. Lorusso, G.
Lotay, R. Lozeva, D. Lubos, C. Magron, F. Molina, I. Matea, K. Matsui, M. Matsushita,
B. Melon, D. Mengoni, B. Meyer, S. Michimasa, T. Miyazaki, V. Modamio Hoybjor, S.
Momiyama, C.-B. Moon, A. Montaner-Piza, A.I. Morales, P. Morfouace, S. Morimoto, K.
Moschner, D. Mucher, E. Nacher, J. Nagumo, H. Naidja, T. Nakao, T. Nakatsukasa, D.R.
Napoli, F, Naquvi, M. Niikura, H. Nishibata, S. Nishimura, I. Nishizuka, C. Nita, F.
Nowacki, A. Odahara, K. Ogawa, H. Oikawa, R. Orlandi, S. Ota, T. Otsuka, H.J. Ong, S.
Orrigo, M. Rajabali, J. Park, Z. Patel, A. Petrovici, F. Recchia, V. Phong, Zs. Podolyak,O.J. Roverts, L. Prochniak, P.H. Regan, S. Rice, E. Sahin, H. Sakurai, K. Sato, H.
Schaffner, H.Scheit, P. Schury, C. Shand, Y. Shi, S. Shibagaki, T. Shimoda, Y. Shimizu,K. Sieja, L. Sinclair, G.S. Simpson, P.-A. Soderstrom, D. Sohler, I.G. Stefan, K. Steiger,
D. Steppenbeck, K. Sugimoto, T. Sumikama, D. Suzuki, H. Suzuki, T. Tachibana, K.
Tajiri, S. Takano, A. Tashima, H. Takeda, Man. Tanaka, Mas. Tanaka, Y. Takei, R.
Taniuchi, J. Taprogge, K. Tajiri, T. Teranishi, S. Terashima, G. Thiamova, K. Tshoo, Zs.
Vajta, J. Valiente Dobon, Y. Wakabayashi, P.M. Walker, H. Watanabe, A. Wendt, V.
Werner, O. Wieland, K. Wimmer, J. Wu, Q. Wu, F.R. Xu, Z.Y. Xu, A. Yagi, S. Yagi, H.
Yamaguchi, K. Yamaguchi, T. Yamamoto, M. Yalcinkaya, R. Yokoyama, S. Yoshida, K.
Yoshinaga, G. Zhang

EURICA WS (2016 Sep.)

Acknowledgement:
Euroball Owners Committee
PreSPEC, GSI, IBS-RISP

Acknowledgement: Gammapool, Preepc, IBSBRIKEN Collaboration
RIKEN :IFIC:
NPL:
W. Michigan:
Univ. Edinburgh:
TRUMF:
Daresbury Lab. :Univ. Tennessee:
ORNL:
Univ. Hong-Kong:KEK:
Univ. Tsukuba:
Univ. Guelph:
Univ. Surrey:
MTA ATOMKI:CENBG:
Peking Univ. :S. Nishimura, P.H. Vi, K. Matsui, G. Kiss. P.-A. Söderström,
H. Sakurai, T. Isobe, H. Baba, T. Kubo, N. Fukuda, H. Takeda,
H. Suzuki, N. Inabe, T. Sumikama, S. Kubono
A. Algora, A. Montaner, B. Rubio, C. Domingo Pardo, J. L. Tain,
S. Orrigo, J. Agramunt, A.I. Morales, V. Guadilla
G. Lorusso
A. Estrade
C. Griffin, P.J. Woods, T. Davinson, D. Kahl
I. Dillmann, R.Caballero-Folch
John Simpson
K. Kolos, R. Grzywacz, S. Go
K.P. Rykaczewski,
Z.Y. Xu, J. Lee, J. Liu
H. Miyatake, Y. Watanabe, H.S. Jung
S. Kimura, M. Mukai
P. Garrett
P. Regan, Z. Podolyák, W. Gelletly
Z. Dombrádi, D. Sohler, Z. Fülöp
S. Grévy , P. Ascher, B. Blank, M. Gerbaux, J. Giovinazzo,T.Kurtukian-Nieto, C. Lederer
Jin Wu, Z.H. Li

Summaryhalf-life（sec）

EURICA Data( 2012 – 2016 ) … 440 isotopes
New Isotopes … 7 ( +44 )Delayed γ … 37

Beta-decay half-life … 144 + 92 / 26

Delayed neutron … 5

Isomer … 14

Proton emission … 382
50

BRIKEN (2016 - )
50
28

28

Delayed neutron … (100 ~ 200 )Beta-decay half-life … (40 ~ 80)
Mass by TOF à ( ? )New beta-decay half-lives play important rolein formation of 2nd peak and rare-earth peak