Doppler Broadening

Theory of Dopler Broadening

Photon emmision along direction of fission fragment velocit

$E_{shift} = E_{photon} \frac{1-\beta \cos(\theta_{photon}^i)}{\sqrt{1-\beta_i^2}}$ = amount of energy the gamma ray was shifted by

where $E_{photon}$ is the Doppler-shifted $\gamma$-ray energy which was measured

$cos\theta_{photon1}$=-$cos\theta_{1}$ for an excited fragment in det-1
$cos\theta_{photon2}$=-$cos\theta_{2}$ for an excited fragment in det-2

$\theta_i$ is the polar emission angle of excited fragment and $\beta_i$ the fragment velocity

$\beta_i$=0.04634$\sqrt{\frac{E_i[MeV]}{A_i[u]}}$

Our Calculations

For example for energy E=2617 keV and the fragment velocity v=$10^9$ cm/s(speed of light c=3x$10^{10}$ cm/s, $\beta$=0.033, $\sqrt{1-\beta^2}$=0.999455352)
We obtained the following results for different angles between the direction of the fission fragment propagation and the direction of the gamma emission

(i) $\theta$=$0^0$

$E_{shift}$=2532.02 keV

(ii) $\theta$=$90^0$

$E_{shift}$=2618.43 keV

(iii) $\theta$=$180^0$

$E_{shift}$=2704.83 keV

FWHM(for energy 2617 keV)=2.5 keV(experimental data)

Energy difference $E_{shift180^0}$-$E_{shift}$

Cf-252 Fission

Photon Spectra from Cf-252

References: http://prola.aps.org/pdf/PR/v104/i3/p699_1

Smith, A. B.; Fields, P. R.; Friedman A. M., Physical Review, vol. 104, Issue 3, pp. 699 - 702

Measurements in the Beam test lab with HpGe and BC408

June 15,2007 Cf-252 measurements with HpGe & neutron sensitive scintillators in coincidence
June 19,2007 Cf-252 measurements with HpGe & neutron sensitive scintillators in coincidence
June 19,2007 Cf-252 measurements of gamma-spectrum using HpGe ungated