laser spectroscopy study on the neutron-rich and neutron-deficient te isotopes

Brigitte RoussièreINTC May 24, 2004

Laser spectroscopy study on the neutron-rich and neutron-deficient Te isotopes

Laboratoire Aimé Cotton, Orsay, FrancePhysics Department, McGill University, Montréal, Canada

Laboratoire de Physique Subatomique et de Cosmologie, Grenoble, FranceInstitut für Physics der Universität Mainz, Mainz, Germany

Institut de Physique Nucléaire, Orsay, FranceCentre de Spectrométrie de Nucléaire et de Spectrométrie de Masse, Orsay, France

• Physics motivations• Experimental setup• Tests on stable beams : - production - efficiency and IS measurements• Beam time request


Laser spectroscopy <r2> from IS

, Qs from the hyperfine structure

the sign of could be determined in 7 casesthe value with its sign in 7 cases morethe Qs value with its sign in 13 cases

the isomeric shift could be measured in 7cases

the isotope shift could be determined in 17 cases


Laser spectroscopy <r2> from IS

, Qs from the hyperfine structure

Neutron-deficient isotopes, N<82 : to search for

dynamic effects

Neutron-rich Te isotopes near N=82 : to study the variation

of the kink at N=82Te

?

?


COMPLIS

resonant ionization

spectroscopy on

laser-desorbed atoms

COMPLIS• frequency scanning• mass selection by TOF• delay between collection and desorption,

to discriminate between m and g when T1/2

are different : 133,131,129Te

SIINODE• frequency set to a resonant transition• ions collected on the tape and transported in front of a -detector• to discriminate between m and g, when T1/2

similar or both long, but -rays observed in the m and g decay different : 121,119,115Te


Ta cathode

NiTe alloy

Insulators made of boron nitride

Kr inlet

Ion source designed and built to produce stable beams of tellurium


Tests performed with the tellurium stable beams

• graphite 5890 type desorption power 2 mJ pyrolytic desorption power 1mJ

• ionization schemes

Efficiency measured on sources with 1013 atoms of 128Te :5×10 9 too low !!

No auto-ionizing level has been found


provided by the frequency tripling of a Nd-YAG laser

to increase the ionization efficiency

overall efficiency measured on 1013, 1012 and 1011 stable

Te collections : = 5×107 gain ~ 100 OK !

Tests performed with the tellurium stable beams

Frequency scan using spread source (2×1011 atoms of 126,128,130Te on 2 cm graphite width) :• step of 30 MHz in UV• 5×108 Te atoms available for each a frequency step

equivalent to an on-line experiment evidence of our ability to perform measurements on radioactive isotopes


Beam time request

ISOLDE Te isotope study from the neutron mid-shell to the nuclei located beyond the neutron shell closure at N = 82

Neutron-rich isotopes

UCx + hot plasma ion source Cs to be reduced Te produced directly A = 129 up to 136 odd-A : g.s. and isomeric state with different T1/2 17 shifts

Neutron-deficient isotopes

Ce2O + hot plasma ion source Te produced directly A = 121 down to 112 odd-A : T1/2 for g and m both long or rather similar SIINODE 21 shifts

Ce2O + plasma ion source with cooled transfer line Te obtained from the Xe and I decay odd-A : mTe not fed by the decay of I means to obtain pure collections of gTe 4 shifts

In total : 38 shifts (+ 4)

laser spectroscopy study on the neutron-rich and neutron-deficient te isotopes

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