SiPMs readout and control with FPGA/SoC

CONVENER	G. Felici (LNF)
LecturerS	D. Badoni (INFN-RM2), M. Beretta (LNF)
TUTORS	D. Badoni (INFN-RM2), M. Beretta (LNF), M. Anelli (LNF), M. Gatta (LNF), P. Albicocco (LNF)
LOCATION	Alte Energie Building. 36 (T73 Bd. 36 / LHCb muon chamber assembling hall)

The aim of the activity is the design, implementation and test of a fully working tracking system made of scintillator strips, Silicon Photo Multipliers (SiPMs), readout electronics and dedicated power supply with remote control. The system is supposed to be used both with cosmic ray for educational activities or as an hodoscope for trigger purpose.

SiPM sensors have been selected for LAB activity because these devices are promising to find a widespread use in many fields such as high energy and astro particles physics experiments as well as nuclear medical imaging applications like Positron Emission Tomography.

The program foresees a set of lab activities covering the key aspects of the project and is, grossly, summarized in the following list:

SiPM sensors and related readout/power supply electronics: description and CAD (SPICE) simulations of the full chain response.
FPGAs: devices and developing environment introduction. Simulation of a section of the readout architecture by means of Xilinx developing boards.
Characterization of the readout electronics (gain and noise), single layer tracker setup and, finally, detector and readout electronics integration.

Laboratory Program

DAY #1

GOALS:

After a short introduction on the working principle and key applications of SiPM sensor the students will gain some insights on sensor modelization and electronic circuit simulation. Simulation results will be afterwards compared with a real system response to check simulations reliability.
LAB ACTIVITY INTRODUCTION - D. Badoni (INFN-RM2):
• Introduction to SiPM
• SiPM readout and supply techniques
LAB - D. Badoni (INFN-RM2), M. Anelli, G. Felici
• SiPM output signal simulation (SPICE)
• SiPM readout and power supply circuit simulation (SPICE)
• Scintillator telescope system hands on activity (scintillator strips assembling)

DAY #2

GOALS:
Students will learn the Field Programmable Gate Arrays (FPGA) possibilities ad applications in modern HEP experiments. Gradually students will familiarize with the basic VHDL concepts and constructs and with the developing environment by means of simple VHDL examples. Hands on activity foresees the use of the XILINX developing boards.
LAB ACTIVITY INTRODUCTION - M. Beretta
• Introduction to FPGA
• Introduction to the XILINX FPGA developing environment and VHDL coding language
LAB - A. Balla, M. Beretta, G. Felici
• ISE/EDK (Xilinx) based workshop (Design/Simulation/Implementation based on VHDL and SPARTAN-3AN developing board). Implementation of a simple code to acquire digital input signals.

DAY #3

GOALS:
Students will be involved in the design of a SiPM based scintillator tracker. Finally the students will partecipate in the assembling of one tracker layer. Hands on activity foresees, besides the assembling of scintillators and SiPMs, the test of front-end electronics, and, finally, the functional test of the full system.
LAB ACTIVITY INTRODUCTION - G. Felici
The Tracker System design
• Requirements
• System definition
• Components selection
LAB - M. Anelli, G. Felici, M. Gatta
• Scintillator assembling
• front-end electronics test
• Single layer assembling

DAY #4

LAB
• Full system test and working point definition
• Test Beam activity

COURSE DOWNLOADS

DAY 1

INTRODUCTION

LABORATORY (ANALOG SIMULATION)

DAY 2

INTRODUCTION

LABORATORY (DIGITAL SIMULATION)

DAY 3

LABORATORY (DIGITAL SIMULATION)

ANALOG SIMULATION: this course is based on Cadence PSpice simulation tool (a subset of the Cadence Allegro design framework for PCB layout). Nevertheless free of charge Spice based simulator are available from LINEAR TECHNOLOGY or TEXAS INSTRUMENTS.

VHDL: the course is based on Xilinx ISE Design Suite. The suite has been discontinued in favor of Vivado Design Suite, that has the same features of ISE with additional support for System-On-Chip (SoC) development. Despite Xilinx released the last version of ISE in October 2013, the development environment is perfectly suitable for the aim of this course (moreover Vivado Design Suite do not support boards based on Spartan 3 FPGA).

A free of charge version of this software is available from Xilinx site (ISE WebPACK Design Software). Although some limitations (for example Platform Studio can manage only the three smallest ZYNQ devices) the software allows to get started with most of the Xilinx products.

A free of charge version of the Vivado Design Suite is available as well (Vivado WebPACK Edition) providing access to basic Vivado features and functionality.

There are a plethora of sites providing VHDL tutorials, but, as the best way to learn something is to practice we suggest starting from VHDL Tutorial: Learn by Example. In spite of publication date it provides coincise but clear explanation of the main VHDL construct and numerous examples to practice.

There are also many books about VHDL; we suggest "VHDL for Programmable Logic" by Kevin Skahill and FPGA PROTOTYPING BY VHDL EXAMPLES (XILINX SPARTAN 3 VERSION) by Pong P. Chu.

Because we can consider VHDL an "hardware" oriented language, an evaluation board is an indispensable tool to learn it. FPGA evaluation board prices ranges from 50 to some thousands of Euros according to the required features. We suggest to buy boards supported by the Vivado Design Suite e.g. the ZedBoard or the MicroZed board. If you are interested in MicroZed board have the Adam Taylor E-book MicroZed Chronicles contains a collection of his articles about MicroZed board capability.

TRACKER:

DETECTOR ASSEMBLING:

SCINTILLATOR STRIPS