Nuclear Physics A 770 (2006) 126–140 Angular momentum dependence of the giant dipole resonance width in excited nuclei of mass A ∼ 150 D.R. Chakrabarty a,∗ , V. Nanal b , V.M. Datar a , Suresh Kumar a , A. Mitra a , E.T. Mirgule a , R.G. Pillay b a Nuclear Physics Division, Bhabha Atomic Research Centre, Mumbai 400 085, India b Tata Institute of Fundamental Research, Mumbai 400 005, India Received 24 January 2006; received in revised form 21 February 2006; accepted 23 February 2006 Available online 22 March 2006 Abstract Gamma ray spectra in the energy range of ∼4–25 MeV were measured in the reaction 28 Si + 124 Sn at E( 28 Si) ∼ 150 MeV in coincidence with low energy γ -multiplicities. The spectra were analysed using a simulated Monte Carlo CASCADE code. The centroid energy and width of the giant dipole resonance were extracted for various multiplicity windows. The average angular momentum and temperature of the final states populated after the giant dipole photon emission range from ∼25 ¯ h and 1.5 MeV to ∼56 ¯ h and 1.3 MeV, respectively. The extracted widths are almost constant for the lower multiplicity windows and show an increase of ∼1.4 MeV at the highest window. The nuclei are expected to be near the liquid drop regime and the experimental results are not inconsistent with the liquid drop behaviour.  2006 Elsevier B.V. All rights reserved. PACS: 24.30.Cz; 25.70.Gh; 27.70.+q Keywords: NUCLEAR REACTIONS 124 Sn( 28 Si, X), E ∼ 150 MeV; measured high energy γ spectra vs. low energy γ multiplicity; deduced angular momentum dependence of giant dipole resonance parameters 1. Introduction The thermal shape fluctuation model (TSFM) [1,2] is generally successful in explaining the temperature (T ) and angular momentum (J ) dependence of the giant dipole resonance (GDR) * Corresponding author. E-mail address: drc@barc.ernet.in (D.R. Chakrabarty). 0375-9474/$ – see front matter  2006 Elsevier B.V. All rights reserved. doi:10.1016/j.nuclphysa.2006.02.012