POLAND - Low Current Profile Measurement Readout System

Abstract

The development of a 32 channel readout system for low-current profile measurements called POLAND (Profile Acquisition Digitiser) was done in collaboration between the Beam Instrumentation (LOBI) and the Experiment Electronics (CSEE) departments. This electronic system is capable to read out beam diagnostic devices like Secondary Electron Monitor (SEM)-profile grids, Multi-Wire Proportional Chambers (MWPC), Ionisation Chambers or similar devices of the future FAIR accelerator system. Transverse beam profiles with a time resolution down to the microsecond range can be measured with POLAND. After intensive tests with a prototype version in recent years[1], the complete readout system, close to the final version, has been built in 2013. It contains the current-tofrequency converter units based on the QFW ASIC[2], the logic unit based on an FPGA and an optical readout for data transfer to a host PC, mounted all together in a 1U 19” rack crate. The system is designed to be read out via FESA or MBS, two standard data acquisition systems for FAIR. Together with different diagnostic systems, POLAND was tested in 2013 at different beam-tests at COSY and HIT. The POLAND readout system The developed hardand software is described in [1] and in detail in [3]. The main changes from the previous version are: a compact but maintenance-friendly design, higher time resolution during the beam pulse measurement, and a daisy chain readout for easy expansion of the number of readout channels. A photography of a POLAND readout unit is shown in Fig. 1. The system has been intensively tested in laboratories of CSEE and LOBI. During this time the FPGA software has been improved and further developed. A first test under beam conditions was done in summer 2013 at COSY in Julich. Here the new electronics was used for monitoring the 2 GeV proton beam. A significant improvement in beam analysis compared to existing systems was achieved. Also the time-resolved beam profile was measured to analyse the extraction structure of the COSY beam. A typical 3D measurement of a time-resolved beam profile is shown in Fig. 2. Within a second beam test at HIT medical accelerator facility in Heidelberg both the software improvements of the readout system and the new detector components connected to POLAND could be tested. ∗ s.loechner@gsi.de Figure 1: Picture of a 32 channel readout system, including the four QFW units (left side) and the FPGA logic unit (middle). The complete system fits into a 1U 19” rack crate. All connectors are on the back side. Figure 2: Time-resolved vertical beam profile measured at the 2013 COSY proton beam test. The beam extraction time was 7s with an ”extra” short pulse at the end of the extraction.