R K SINGH, R K MOHANTA, R HIPPLER* and R SHANKER

Atomic Physics Laboratory, Physics Department, Banaras Hindu University, Varanasi 221 005, India
* Fachbereich Physik, Universitaet Greifswald, Domstrasse 10a, 17487-Greifswald, Germany

Email: rshanker@banaras.ernet.in

Abstract.

Development of a new electron-recoil ion/photon coincidence setup for investigating some of the electron induced collision processes, such as electron bremsstrahlung, electron backscattering, innershell excitation and multiple ionization of target atoms/molecules in bombardment of electrons having energies from 2.0 keV to 30.0 keV with solid and gaseous targets is described. The new features include the use of a compact multipurpose scattering chamber, a time-of-flight spectrometer for detection of multiply charged target ions, a 45^o-parallel plate electrostatic analyzer for measuring energy and angle of the ejected electrons, a room temperature high resolution Si-PIN photo diode X-ray detector for counting the collisionally induced photons, a coincidence data acquisition system consisting of a 200 MHz Pentium based 8K-multichannel analyzer and a standard network of a fast/slow coincidence electronics. In particular, the details of design, fabrication and assembly of indigenous components employed in the setup are presented. Selected experiments planned with the setup are mentioned and briefly discussed. A report on performance, optimization, efficiency, time resolution etc. of the time-of-flight (TOF) spectrometer and that of the 45^o-parallel plate electrostatic analyzer (PPEA) is presented. Test spectra of electron-recoil ion coincidences, energy distribution of ejected electrons and characteristic plus non-characteristic X-ray spectrum are illustrated to exhibit the satisfactory performance of the developed setup.

Keywords:  Time-of-flight spectrometer; parallel plate electrostatic analyzer; electron bremsstrah- lung; electron backscattering; multiple ionization.

Pacs Nos.  07.81.+a; 34.80.Dp; 41.60.-m