132Sn from the β-decay of In isotopes

Gamma and fast-timing spectroscopy around

132 Sn from the b -decay of In isotopes

J. Benito¹, L.M. Fraile¹, A. Korgul², M. Piersa², R. Álvarez-Rodrigez³,G. Benzoni⁴, T. Berry⁵,

M.J.G. Borge⁶, M. Carmona¹, K.Chrysalidis⁶, G. Correia⁶, C. Costache⁷, H. De Witte⁸, T. Day Goodacre⁶, D. Fedorov⁶, G. Fernandez-Martinez⁹, D. Galaviz¹⁰, R. Grzywacz¹¹,

C. Henrich⁹, M. Huyse⁸, A. Illana⁸, Z. Janas², K. Johnston⁶, V. Karayonchev¹²,

M. Kicinska-Habior², R. Lica^6,7, M. Madurga⁶, I. Marroquín¹³, B. Marsh⁶, C. Martínez¹,

C. Mazzocchi², K.Miernik², R. Mihai⁷, B.Olaizola¹⁴, S. Paulaskalas¹¹, J.-M- Regis¹², S. Rothe⁶, V. Sánchez-Tembleque¹, G. Simpson¹⁵, Ch. Sotty⁶, L. Stan⁷, M. Stanoiu⁷, M. Stryjcyk⁸,

A. Turturica⁶, J.M. Udías¹, P. Van Duppen⁸, V. Vedia¹, A. Villa¹, B. Walters¹⁵, N. Warr¹²

1Grupo de Física Nuclear, Universidad Complutense, CEI Moncloa, Madrid, Spain., ²Faculty of Physics, University of Warsaw, Warsaw, Poland.,³ Universidad Politécnica de Madrid, Madrid, Spain., ⁴INFN, Sezione di Milano, Milano, Italy, ⁵ Deparment of Physics, University of Surrey, United Kingdom; ⁶Isolde-CERN, Geneva, Switzerland.; ⁷,,Horia Hulubei” National Institute of Physics and Nuclear Engineering, Bucharest, Romania;⁸Instituut voor Kern- an Stralingsfysica, K.U. Leuven, Leuven, Belgium; ⁹Institut fuer

Kernphysik, Technidche Universität Darmstadt, Germany., ¹⁰Centro de Fisica Nuclear da UL, University of Lisbon, Portugal;

11Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee, USA; ¹²Institut fur Kernphysik, Universität zu Koln, Koln, Germany; ¹³Instituto de Estructura de la Materia, CSIC, Madrid, Spain; ¹⁴TRIUMF, Vancouver, Canada; ¹⁵LPSC,

IN2P3 (CNRS), Université Grenoble Alpes, Grenoble, France; ¹⁶Departament of Chemistry, University of Maryland, USA.

Presenter: Jaime Benito, UCM ¹

Outline

• Introduction to the

Sn region

• Experimental details.

• Preliminary results for

In decay.

• Preliminary results for

In decay.

• Conclusions

208Pb*

132Sn*

78Ni

100Sn

132

Sn is the only medium-heavy

itself and most of its

can be studied in some detail.

Test the shell-model effective Hamiltonian:

• single particle energies

• 2-body matrix elements of the residual interaction

• effective electromagnetic operators

Motivation

3

 Doubly-closed nuclei

 Test of nuclear models

→ single particle energies, 2-body matrix elements, EM operators

 They are used in model calculations over an extended range of the nuclide chart.

 Properties of these nuclei are important to model the astrophysical r-process.

 Both sides of N=82 along Sn isotopes

Motivation

ISOLDE Experiment IS610

• Bombardment by 1.4 GeV protons on UC

target

• Neutron converter to suppress contaminants.

• In isotopes were ionized with a laser source ISOLDE RILIS.

• In isomer selectivity

• In beams were mass separated with the HRS, and implanted in a tape in the middle of the experimental setup.

5

Ionization: RILIS

 Resonant ionization of atomic structure.

 Highly selective ionization of desired isotope.

 Hyperfine splitting gives a possibility to separate nuclear isomeric states.

RILIS scan for ¹²⁹In, monitored by decay γ-rays

Experimental Setup

Experimental Chamber

• Tape system to reduce the activity of the daughters.

7 Detectors:

• 4 Clover HPGe detectors with good energy resolution for spectroscopy information.

• One fast plastic scintillator (NE111A) as β-detector.

• 2 LaBr₃(Ce) scintillator crystals with good time resolution for timing information.

7

Ion Beam

HPGe Clover

Analog and digital electronincs:

• CFD and 3 TAC for fast-timing analysis.

• Digital DAQ Nutaq XXXVI Reunión Bienal de la RSEF

Analysis Method

g Spectroscopy and Construction of Level-schemes

b -HPGe, b-HPGe-HPGe coincidences

Lifetime measurements

b -Ge-LaBr(t), b -LaBr(t), b-LaBr-LaBr(t), LaBr-LaBr(t) coincidences

De-convolution of slope:

• Slope = T

• Range: 30 ps to 30 ns (or longer)

Centroid shift:

• Shift in centroid position = 

• Range: down to ~5-10 ps

PRELIMINARY RESULTS

b decay of 131 In isomers

 ¹³¹In has three different

isomers g.s. 9/2⁺ , 1/2⁻ and high energy 21/2⁺

 ¹³¹In was ionized using

different laser configurations.

 1/2⁻ and 9/2⁺ isomers were very well separated using a different frecuencies in

narrowband.

 Decay of 21/2⁺ isomer could not be fully separated from the others, but population can be estimated form the

2433 keV9/2+

332 keV1/2-

282 keV21/2-

Narrowband 9/2⁺ isomer

Narrowband 1/2^- isomer

2433 keV9/2+

332 keV1/2-

282 keV21/2-

G.s. half lives of 131 In Isomers

 / 0

e

N

N 

Isomer Preliminary T_1/2

(This work)

T_1/2 (Previous) [1]

9/2+ 260(10) ms 280(30) ms

1/2- 330(20) ms 350(50) ms

21/2+ 330(20) ms 320(60) ms

T

=330(20) ms

[1] Nuclear Data Sheets 131 (2010)

Preliminary, estimated final uncertainty below 10 ms

Half life of the 331-keV state in 131 Sn

Level(keV) E

(keV) J

→ J

T

B(XL) (W.u.)

331.4(1) 331.4(1) 1/2⁺ →3/2⁺ 30(10) ps B(M1)=1.7(6) x 10^-2

 Forbidden M1 transition Dl=2: 3s_1/2 → 2d_3/2

 Preliminar meassurement of the lifetime of 331 keV state by centroid shift method.

 Similar to the half-life of 315 keV state measured in ¹²⁹Sn [1] at ISOLDE in the IDS.

=45(15) ps

Contribution from compton background

M1 effective operator (A. Gargano et al.) 3s_1/2 → 2d_3/2 M1 l-forbidden

Assumes pure M1

131 In 21/2 + isomer decay.

Level(keV) E

(keV) (Preliminary) T

4446.4+x 173.1 ~600 ps

4557.9+x 284.6 ~50 ps

4705.6+x 258.1 <30 ps

 Search for lifetimes of high-lying states from the beta-decay of the

πg_9/2^-1 x νh_11/2⁻¹ f_7/2 ¹³¹In configuration.

 More levels and decay gamma-rays obseved

 Preliminary lifetimes

 M1 and E1 transition rates

 High-multipolarity transitions to low-lying 11/2^–

Investigation of 132 Sn

 Search for states from the expected particle-hole multiplets:

n f

h

n f

d

n f

g

p g

g

 Level lifetimes to provide information on transition rates

from Jan Blomqvist

Not yet identified!

 Under analysis

 Populated in the b-decay of

132In and bn decay of ¹³³In

 Timing analisis over 4-5 MeV excited states in ¹³²Sn

 Preliminary results in agreement with previous results

H. Mach et al., Nuc. Phys. A588 179c (1995)

Level (keV)

E_g (keV)

T_1/2

(this work)

T_1/2 [1]

4416.2 375.1 3.8(2) ns 3.95(13) ns 4715.9 299.6 21(2) ns 20.1(5) ns 4831.0 479.1 ~20 ps 26.0(5) ps 4919.0 203.1 ~100 ps 62.0(7) ps 4942.5 682.0 <50 ps

5629.3 710.3 <15 ps 13.0 ps

Conclusions

• Investigation of excited Sn structure with combined gamma and fast-timing spectroscopy at ISOLDE

• Single particle states above and below N=82 Shell

• Isomerically purified In beams help identification of low-lying structures.

• Analysis of β-decay and β-n branches populating the same nucleus.

• Level-lifetimes to help identification of states.

Work ongoing…

Thank you for

your attention!