BLM System for NSRL HLS PCaPAC 2000, Oct.9 ~ 12, 2000Page 1 PC and CAN Bus in Beam Loss Monitor System for NSRL Yonggang Cui, Beibei Shao Department of Engineering Physics, Tsinghua University Yuxiong Li National Synchrotron Radiation Laboratory

BLM System for NSRL HLS PCaPAC 2000, Oct.9 ~ 12, 2000Page 2 Introduction to NSRL HLS Implementation of BLM System Results and Analysis Conclusions Contents

BLM System for NSRL HLS PCaPAC 2000, Oct.9 ~ 12, 2000Page 3 Introduction to NSRL and HLS First National Laboratory in China dedicated to Synchrotron Radiation 66.35m long, 800MeV electron storage ring – Hefei Light Source, with a 200MeV linac as its injector New Beam Loss Monitor System (BLM System ) installed in Phase II project. Introduction to NSRL and HLS

BLM System for NSRL HLS PCaPAC 2000, Oct.9 ~ 12, 2000Page 4 The System employs PIN-photodiodes BLM detector designed by DESY. Detection efficiency to electrons (MIP) is 30%, 3 magnitudes higher than that to gamma ray Insensitive to gamma ray and background of synchrotron radiation around the electron storage ring The system gives beam losses information by detecting the charged shower particles produced by beam loss electrons when hitting the vacuum wall. Principle of Detecting the Beam Losses Introduction to NSRL and HLS

BLM System for NSRL HLS PCaPAC 2000, Oct.9 ~ 12, 2000Page 5 Scheme of BLM System Structure Distributed system based on CAN bus. PC with Windows 98/NT is employed as console. 16 frontend machines distribute along the storage ring. 12 frontend machines are placed behind the bending magnets. The others locate at interested points, e.g. the end of straight section. Every front-end can drive two BLM detectors CAN BUS PC Console with Windows 98/NT …... Front-end BLM Detectors Implementation of BLM System

BLM System for NSRL HLS PCaPAC 2000, Oct.9 ~ 12, 2000Page 6 Console with 98/NT …... Front-end BLM Detectors Scheme of BLM System Structure Independent System Structure Because the new control system has not finished yet when the BLM system was designed. Integration to the whole system is simple The communication part of console software => Middle layer The displaying part of console software => top layer CAN BUS WS or PC Terminal Ethernet VME or PC Implementation of BLM System

BLM System for NSRL HLS PCaPAC 2000, Oct.9 ~ 12, 2000Page 7 Frontend Machine and Pulse Accumulator Every front-end can be divided into 3 parts: MCU Module CAN Bus Module Counter Module. The pulse accumulator in counting module: Two channels Counting frequency higher than 10MHz Free running ability: working continuously without losing any pulses, even when accessed by MCU EPLD Implemented (ALTERA) CAN BUS Dual-Channel Pulse Accumulator Pulses Input Signal Condition CAN Controller CAN Driver CAN Address ROM ( 8K ) RAM ( 40K ) MC68HC11A1 MCU Clock RS-232 Addr/Data BUS MCU Module CAN BUS Module LED & Control Counter Module Implementation of BLM System

BLM System for NSRL HLS PCaPAC 2000, Oct.9 ~ 12, 2000Page 8 CAN Bus Communication in BLM System CAN Bus High speed differential bus with high reliability and robustness Multi-master and broadcast bus cost-effective design Solution CAN interface board on PC Cheap total solution from Philips for frontend Define the message format of data frames instead of using thee standard CAN application layer, e.g CAL, CANopen The definition is implemented as Simple CAN Application Interface (SCAI) in C language Implementation of BLM System

BLM System for NSRL HLS PCaPAC 2000, Oct.9 ~ 12, 2000Page 9 Implementation of Software CAN BUS Device Driver BeamEyes Application Software (Microsoft Visual C++ 6 with MFC) CAN BUS ISR & I/O Function DAQ Software PC Console Front-end Document: CBeamEyesDoc View 1: CCrossView View 2: CCurveView Display BLM data in histogram Display BLM data in curves Collecting Option Beam Loss Data System Parameters Pointers SCAI Implementation of BLM System

BLM System for NSRL HLS PCaPAC 2000, Oct.9 ~ 12, 2000Page 10 Result I Beam lifetime includes Quantum lifetime Inelastic scattering Touschek lifetime Beam lifetime, esp. quantum lifetime became much more worse due to operators changing the running parameters Results and Analysis

BLM System for NSRL HLS PCaPAC 2000, Oct.9 ~ 12, 2000Page 11 Result II Results and Analysis

BLM System for NSRL HLS PCaPAC 2000, Oct.9 ~ 12, 2000Page 12 Conclusions The System is sensitive enough to detect beam losses. Right selection of BLM detector Correct design of pulse accumulator The BLM system based on PC and CAN bus is fast enough for real-time display. CAN bus is a high speed, high reliability bus. Its a right candidate in field control. PC with Microsoft windows operating system is a reasonable selection in slow speed system. Conclusions

BLM System for NSRL HLS PCaPAC 2000, Oct.9 ~ 12, 2000Page 13 Conclusions (continue) The BLM system can not only detect the beam losses, but also give much more help on machine study. Finding the reason of beam losses Optimizing the storage rings running parameters beam lifetime study Conclusions

BLM System for NSRL HLS PCaPAC 2000, Oct.9 ~ 12, 2000Page 14 Picture of the Frontend Machine

BLM System for NSRL HLS PCaPAC 2000, Oct.9 ~ 12, 2000Page 15 The End