A New Read-out System for an Imaging Pixel Detector G. Bardelloni 2 , E. Bertolucci 1 , A.L.J. Boerkamp 2 , D. Calvet 2,3 , M. Conti 1 , M. Maiorino 1 , P. Russo 1 , J.L. Visschers 2 1 Dipartimento di Scienze Fisiche, Università di Napoli “Federico II” and INFN Napoli, Via Cinthia, I-80126 Napoli, Italy 2 National Institute for Nuclear Physics and High-Energy Physics (NIKHEF), postbus 41882, NL 1009 DB, Amsterdam, The Netherlands 3 Centre de Physique des Particules de Marseille (CPPM), 163 avenue de Luminy, case 907, F-13288 Marseille cedex 9, France Abstract A system has been developed for the control and readout of an electronic circuit (Medipix) designed for medical X-ray imaging applications. This system (MUROS-1) is based on standard commercial analogue and digital I/O boards and a simple dedicated interface. A user-friendly software (Medisoft 3) has been developed to provide full control of the system, including fine tuning of the Medipix circuit, image presentation and post-exposure image processing. I. INTRODUCTION Medipix [1,2] is a low-noise VLSI circuit containing mainly a matrix of 64x64 readout cells, each cell consisting of a preamplifier, a discriminator and a 15-bit counter. This circuit has been developed to be connected to a semi-conductor pixel detector for medical and biological X, β and γ-ray imaging applications. Until now, it was controlled and readout using a rather complex system including a PCI bus to VME bus interface, a VME crate, a custom VME board, a few power supplies and a pulse generator. Reasons to re-design the control and readout system of the Medipix circuit were driven by the necessity to provide easier set-up and usage, compared to the more complex VME-based system. The system should also be easy to adapt to the new generation of Medipix-2 circuits, presently under design, featuring a far larger number of pixels and a higher throughput rate. The new readout system hardware – called Medipix-1 re- Usable Read-Out System (MUROS-1) – controls the Medipix circuit via standard commercial analogue and digital I/O boards. Connection between these boards and the circuit is made via a simple Medipix-1-dedicated interface. The MUROS-1 hardware is controlled by dedicated software, called Medisoft 3 (the VME-based system was controlled by Medisoft 2). This software is able to perform all basic operations needed to control the Medipix circuit as well as special tasks like threshold equalisation or image processing. II. MUROS-1 HARDWARE The Medipix-1 re-Usable Read-Out System (MUROS-1), developed by NIKHEF, is a low-cost acquisition system based on standard commercial components. The small MUROS-1 interface is the only Medipix-1-dedicated component of the system. The more expensive commercial boards may be re- used for other applications, such as the control of the future Medipix-2 circuit. A. MUROS-1 Overview The MUROS-1 hardware is made of a few components: • a standard personal computer (PC), running the Medisoft 3 software, • a standard analogue board AT-AO-10 [3], plugged in the EISA bus of the PC, • a standard digital I/O board PCI-DIO-32HS [3], plugged in the PCI bus of the PC, • a MUROS-1 interface. No other hardware component is needed in the standard configuration (no external power supply, no pulse generator). In the case the Medipix circuit is connected to a semi- conducting sensor, an external high voltage power supply is needed to bias this sensor. The Medipix circuit is usually glued on a printed circuit board (PCB), directly connected to the MUROS-1 interface. Wafer probing of Medipix circuits has also been performed by connecting the probe card to this interface using a shielded flat cable. Figure 1 shows the MUROS-1 interface connected to a Medipix circuit and to the analogue and digital boards. Figure 1: Picture of the MUROS-1 interface, with the two cables from the analogue and digital boards. The PCB plugged in the interface holds a Medipix circuit (not seen on this picture).