Applicability of Parallel Plate Avalanche Detector Systems to Spontaneous Fission from Cf 252

1. Applicability of Parallel Plate Avalanche Detector Systems to Spontaneous Fission from Cf252 Zafar Yasin Pakistan Institute of Engineering and Applied Sciences (PIEAS) Islamabad

2. Outline • Importance of Nuclear Fission • Parallel Plate Avalanche Detectors • Spontaneous Fission • Data Analysis • Introduction to MAX-lab electron Accelerator

3. Introduction • Nuclear fission covers the areas ranging from nuclear structure models to accelerator- driven systems. • Spontaneous fission source 252Cf is used for calibration of detectors. • Photon induced fission is as important as fission induced by nucleons. • Photofission has applications in nuclear waste management. • Parallel Plate Avalanche Detectors (PPADs) are fabricated at MAX-lab and tested using 252Cf. • PPADs will be used to study Spontaneous at the MAX-lab electron accelerator.

4. Principle of Parallel-Plate Plate Avalanche Detectors • PPADs lie among the new categories of gas detectors. • Gas multiplication occurs in a PPAD and number of secondary electrons obey the relation given by, • N (d) = N0 exp (α. d), • where • N0 = number of primary electrons, • d = drift path, • α = first Towsend coefficient, • Voltage pulse generated by a fission fragment is given by where C is the capacitance of the detector.

5. Properties of Parallel-Plate Plate Avalanche Detectors • Capability to handle high count rates up to 105 fissions/s. • Good time resolution up to 500 ps. • Insensitivity to radiation damage. • Clean pulse height separation between fission fragments and lighter charged particles. • High detection efficiency and large solid angles. • Insensitive to neutrons, photons and electrons. • Quite transparent to a high energy photon beam. • Low production cost.

6. Construction of PPADs A rectangular target-detector arrangement used in the experiment.

7. Electrode foils Electrodes frame Construction of PPADs A circular PPAD.

8. Experimental setup for spontaneous fission source 252Cf

9. The reaction chamber in the experimental hall

10. The PPADs mounted inside the reaction chamber

11. PPAD2 Cf252 PPAD1 Pre-amplifier Attenuator Fanout CFD Delay CFD Four fold logicunit ADC2 ADC1 VETO OR/AND Start Gate generator Stop LATCH Scaler2 Scaler1 NIM Fan out OR Interrupt Gate ADC Computer Start Stop2 TDC Stop1 Schematic overview of the electronic setup used to study the spontaneous fission from 252Cf.

12. Count rate as a function of voltage and pressure using a PPAD for a 252Cf .

13. Effect of pressure on count rate at constant voltage.

14. Data analysis • Offline analysis is performed using the computer code ROOT. • The ROOT software is an object-oriented (C++) data analysis package developed at CERN. • It was developed keeping in mind the high energy physics experiments and several laboratories around the world use ROOT for the analysis of data. • For the analysis of Spontaneous and photofission data, we have written C++ codes within the ROOT framework.

15. Data analysis

16. Data analysis Time Spectrum from both PPADs.

17. Data analysis Energy Spectrum from a PPAD.

18. Data analysis A three-dimensional and two dimensional view of the distribution of fission fragments observed with ADC1, x-axis with cut TDC1, versus ADC2, y-axis with cut TDC2.

19. Time resolution If the intrinsic time resolutions of the start and stop detectors are equal, then we can write, Δt2exp = Δt2kin + Δt2geom + 2 Δt2intr In the present geometry the value of the Δtkin comes out to be 0.6 ns and Δtexp 1.25 ns. If we assume the Δtgeom to be .17 ns, then the intrinsic time resolution is 0.76 ns. A three-dimensional view of the distribution of fission fragments observed with TDC1 versus TDC2.

20. Electron gun Linac e- e- MAX I ring e- Nuclear physics area Synchrotron radiation MAX-lab

21. Magnet Photons Radiator e- Target Focal Plane Detectors Reaction Product Faraday cup Detector Stop Start TDC Photon tagging Eγ = E0 - Er

22. Thank you