STUDY OF MULTIBODY DECAYS OF HEAVY NUCLEI USING LIGHT ION - - PowerPoint PPT Presentation

STUDY OF MULTIBODY DECAYS OF HEAVY NUCLEI USING LIGHT ION SPECTOMETER (LIS)

Chumisani Larry Nduna Supervisor : Mr. V.D Malaza Supervisor: Mr A.O.Strekalovsky

OUTLINE

 Introduction Light Ion Spectrometer (LIS) Setup Experimental Challenges Calibration Process Results Conclusion

Introduction

 Nuclear Fission – Process where a heavy nucleus such as Uranium decays into two fragments of roughly equal masses, a process known as binary fission.  Ternary Fission – In this decay channel the nucleus splits into three fragments with the third particle being too light compared to the main fission fragments.  A new ternary decay of low excited nuclei called Collinear Cluster Tri- partition (CCT) was observed.  Collinear Cluster Tri-partition (CCT) was observed in the fissioning of 252Cf , using time-of-flight spectrometer known as Light ion Spectrometer (LIS)

Light Ion Spectrometer (LIS) Setup

Experimental Challenges

 The masses of fragments defining the modes under investigation differ radically.  There is a challenge which involve measuring the correct energy and time-

• f-flight of heavy ions in the wide range of energies and masses using PIN

diodes as “stop” detectors.  This is due to the negative influence of the known “plasma delay” in registering time-of-flight of fission fragments and the “pulse-height defect” (PHD) in registering energy of fission fragments using semiconductor detectors.  To solve this challenge we have a special process called Calibration process.

Calibration Process

 Calibration process is divided into three steps:

• 1. Time calibration
• 2. 3-Point calibration
• 3. True calibration (PHD & PD taken into account)

 Time calibration and 3-point calibration – mass is approximated

Conclusion:

 The 3 Point Calibration process presented above proves to be a reliable mass approximation procedure.  But it should be noted that the mass from the 3 point calibration suffers from the PHD and PD.  A special procedure known as “True Calibration” has been developed which takes into account the PHD and PD.  Therefore a true mass of the fission fragments can be obtained from this procedure.