A cost effective scheme for detector pulse processing State machine operational flow Hardware implementation The embedded pulsed reset as a cost effective alternative scheme in pulse processing is functionally verified in an alpha particle spectroscopy application. The issue of charge injection requires further fine tuning of the design with the use of ultra low charge injection switches and fine tuning of the reset signal shape. Conclusions Results Uses analog Gaussian pulse shaping filters to minimize the effects of front-end electronic noise and reduces the pulse duration to eliminate pulse pile up. The shaped pulse peaks are subsequently digitized using low speed digitizers. Best suited for high performance laboratory instrumentation. Portable radiation monitors with spectroscopy capability has increased in the recent years in applications like [1]. environmental quality monitoring study of geological processes nuclear fuel cycle and nuclear safeguards. The design requirements of these systems can be summarized as. A major drawback of the conventional schemes is the high implementation cost. Present work Exploring a novel cost effective pulse processing scheme using recent reconfigurable mixed signal hardware implementation platforms and ultra low charge injection analog switches. References A novel pulse processing scheme using embedded pulsed reset charge sensitive preamplifier G. Prasanna*, J. Jayapandian, O.K. Sheela and G. Amarendra Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam ,Tamil Nadu, India. Portable radiation monitoring applications - the need for alternative schemes Pulse processing in nuclear spectroscopy The “front-end” of a nuclear spectroscopy system consists of the detector and the charge sensitive preamplifier. The preamplifier output is a standard tail voltage pulse with a peak voltage proportional to the energy deposited by any radiation in the detector active volume. Pulse processing involves reducing the deleterious effects of inherent front-end electronic noise and pulse pile up phenomena on the peak value of the tail pulse. Firmware operational flow Firmware controlled pulsed reset scheme with low speed digitizer and a simple state machine. Embedded pulsed reset- operational flow & implementation Existing pulse processing schemes Analog pulse processing Digital pulse processing Uses very high speed digitizers of ~ 40 Mega samples per second to directly digitize preamplifier pulses. The samples are subsequently numerically analyzed using high speed digital signal processors. Best suited for high performance low power applications like space instrumentation. SchemeResolutionThroughputTemperature stability Cost AnalogHigh LowHigh DigitalHighModerateHigh Characteristics summary of existing schemes ResolutionThroughputTemperature stability Cost Moderate HighLow The turning ON of a very high OFF resistance CMOS analog switch used as the feedback element is performed after every single digitization of the preamplifier output pulse using a unique reset signal generated through a firmware operation in a microcontroller platform. Pulsed reset using low charge injection solid state switches drastically reduces the predominant feedback resistance thermal noise in the preamplifier output. The state machine operates in parallel to detect pulse pile up and notify the firmware. Implementation platform- The PSoC System implemented on Programmable System on Chip (PSoC) mixed signal hardware platform [2]. PSoC is a mixed signal IC architecture consisting of programmable analog and digital blocks, a CPU subsystem with programmable routing and interconnect enabling quick implementation of innovative design schemes. (a) (c) (b) (a) Pulsed reset scheme [3] implemented with OPA-656 based charge sensitive preamplifier and MAX-4594 CMOS analog switch. (b) PSoC development kit for implementation of the firmware operation. (c) Differentiator and comparator cascade for generating pulse-edge signal. Alpha Spectrum from a standard triple alpha source obtained with LabVIEW ® based multi channel analyser shows distinct energy peak of each isotope with moderate resolution. Resolution degradation happens due to charge injection in the switch which causes baseline shift. Charge injection reduces with proper shaping of the reset signal and with use of recent switches with ultra low charge injection. 1. García-Toraño Eduardo. Applied radiation and isotopes 64.10, (2006). 2. Cypress Semiconductor. PSoC® 5LP 2015 [cited Jul]; Available from: 3. Knoll, Glenn F, Radiation detection and measurement, New York, John Wiley & Sons, 2000, pp