The 3 MeV pygmy resonance in 163,164Dy

Hilde-Therese Nyhus

Department of Physics University of Oslo

Introduction Motivation for analyzing these nuclei Experimental method Level density Gamma-ray strength function

Motivation

MotivationVarious other rare earth nucleihave been studied using theOslo method, one has then measured a width of the pygmyresonance between 1.2-1.5 MeV. This contradicts what has been measured in Prague for other rare earth nuclei, where abouthalf the width has been found.

The reactions used to produce the nuclei

The reactions used to produce the nuclei

At Oslo Cyclotron Laboratory:

164Dy(3He, 3He*)164Dy164Dy(3He, )163Dy

The reactions used to produce the nuclei

At Oslo Cyclotron Laboratory:

164Dy(3He, 3He*)164Dy164Dy(3He, )163Dy

In Prague:162Dy(n, )163Dy

Experimental method-Gate on the various particles to construct coincidence matrix.

Coincidence matrixes

163Dy 164Dy

Experimental method-Gate on the various particles to construct coincidence matrix.

-Unfold the gamma spectrum and generate first generation matrix.

First generation matrixes

163Dy 164Dy

Experimental method-Gate on the various particles to construct coincidence matrix.-Unfold the gamma spectrum and generate first generation matrix.

-The experimentally obtained first generation matrix is according to the Brink-Axel hypothesis proportional to the level density and gamma ray strength function.

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P(E x,Eγ )∝T(Eγ )ρ(E x,Eγ )

Level density in 163,164Dy

Preliminary

163Dy 164Dy

Gamma-ray strength function with pygmy resonance

Gamma-ray strength function in 164Dy, with a pygmy resonance.

Gamma-ray strength function in 163Dy, with a pygmy resonance.

The width of the pygmy resconance masured in Prague is 0.6 MeV

163Dy 164Dy

Preliminary

Gamma-ray strength function with pygmy resonance

Gamma-ray strength function in 163Dy, with a pygmy resonance.

The width of the pygmy resconance masured in Prague is 0.6 MeV

163Dy

Preliminary