The Development of an Ionization Profile Monitor for use in the Tevatron Lawrence Short Bull SJSU, San Jose, CA Supervisor: Andreas Jansson Beams Division, FNAL SIST Summer 2003

Agenda Introduction Principles of Operation Design Details Experiments Conclusion Acknowledgements

Introduction Quantities of Interest  Luminosity  Emittance Emittance Monitoring Devices at FNAL  Flying Wire  Synchrotron Light Monitor  Ionization Profile Monitor (IPM)

Luminosity Run II Goals: peak L 5.1E31 cm^-1sec^-1, integrated 2fb^-1

Emittance projection onto x/y axis provides transverse beam dist. r.m.s. value of beam density distribution provides measure of beam size Beam size given as r.m.s of Gaussian beam profiles Initial distribution not quite Gaussian, by time final energy reached is very good approximation.

Emittance monitoring in Tevatron Flying Wires  Evasive diagnostic tool Synchrotron Light Monitor  Non-evasive Reported emittances show discrepancy Potential emittance monitoring in Tev  IPM  Schottky Detector

Why an IPM for the Tev? Run II Instrumentation Motivations Transverse and longitudinal emittance preservation Real time operational tuning & monitoring  Tev IPM provides turn-by-turn profile measurements for transverse injection matching  Sync lite only “on-line” transverse profile monitor available during store (insuff. 150 Gev)

IPM Fundamentals Provide transverse beam profiles: vertical & horizontal Residual gas ionization occurs with each bunch passage Collection of ions/electrons with electric clearing field Combat space charge effects Utilizes microchannel plate(MCP) for charge multipliction Amplified signal of charge collected on anode strip Signal integrated, amplified, and digitized Sent from memory to processor to provide histogram profiles

MCP fundamentals Array of dynodes Contain large number ~1E4- 1E7 Aspect ratio: Diameter: 5-25 microns Intrinsic impedance: ~1E9ohm Intrinsic capacitance: ~ 30pF Gain: 1E4-1E7 Gain degradation proportional to extracted charge

QIE ASIC Charge, Integration, Encoding Input current integrated over 4 ranges Pipelined into 4 stages at 25nsec per stage Output is 5 bit mantissa, 2 bit range exponent, 2 bit cap ID in calibration mode the FADC is strictly linear with 32 linear 0.87 fC/count Input charge: 6.1fC – 26fC

EB Anode strips Beam MCP Tev IPM Design 36 X 36 proton and pbar bunches Time between bunches ~396ns Bunch length ~ 3ns r.m.s., 18-20ns Only ~1000 e liberated during ionization Electronics must be low noise Need Faraday screen to protect detector from image 53MHz Pull only signal through vacuum flange, reference vacuum Anode to ground completely floating screen

Block diagram/data flow chart serializer 16 serial links (optical fiber) ~1.6 Gbits/s/link ~23 Gbit/s total Sample clock (17.6 MHz) Anode stirp signals (~128) 16 Proton revolution marker KwameVince, Mark et al PCIX bus DMA xfer Burst mode ~1 Gbit/s Pbar revolution marker QIE (8 QIEs) optical driver Fast (wide) memory FPGA Data Header byte QIE reset QIE mode Header card 53 MHz RF Timing card Injection event off-the-shelf in tunnelin upstairs PC GPIB controller To power supplies PCI BUS

MI IPM Studies Utilized IPMM1H & IPMM2H Investigate effects of a varying bias voltage for MCP in detectors ACNET variables I:HxMCPV, I:HxPMEM[ ],I:HxPMSG[ ] datalogged at node TevJA Settings on LabView interface determine what turn number was datalogged Two ranges were studied IMPM1H IPMM2H

MI_IPM: H1 results

MI_IPM: H2 results

MI_IPM: H2 better resolution

MI_IPM: H2 up the ramp

QIE Noise Measurements The noise floor of the CKM QTBB floor was determined Noise for various cable configurations was to be determined Data Multiplexing QIE A QIE B 16 bit SERDES w/ 8B/10B Clock dist. ckt. 40MHz

Pedestal = r.m.s = Noise floor channel A: input impedance = 50 ohm

Noise floor per cap ID: input impedance = 50 ohm Cap ID 0Cap ID 1 Cap ID 2 Cap ID 3 r.m.s = r.m.s = r.m.s = r.m.s =

noise, e-gain factor cap id cap id cap id cap id Gain factor for channel: Noise for channel: 3171e Determination of Gain Factor per cap ID: Zin = 50 ohm

Capacitance input to either signal or reference inputs Peculiar behavior displayed, further investigation required

Configuration of interest: input cap. To both signal & reference Noise levels appear within tolerances for design

Noise floor channel A: input impedance = 93 ohm Pedestal = r.m.s. = Similar results as 50 ohm case when individual cap id’s examined

Determination of Gain Factor per cap ID: Zin = 93 ohm Noise for channel: 3123e Gain factor for channel: noise e gain factor cap id cap id cap id cap id Less noise, relatively the same gain factor for the channel than the 50 ohm setting

Cable Test 100 ohm twisted pair cable connected to both signal and reference Length of cable = 3.75 m Shield of each cable connected Return for each cable connected Zin = 93 ohm, noise is 6,808 e Zin = 50 ohm, noise is 10,844 e Zin = 93 ohm Zin = 50 ohm

Conclusion Emittance as reported by IPM very sensitive to output current; N2 leak must be added with care, low gain MCP MCP test stand will be used to study MCP properties for this project in addition to future projects. Also to diagnose MCP’s coming out of the machine If QIE noise results correct, good thing. Seem slightly low. Tev IPM up for technical DOE review in Oct., things look good and will more than likely be commissioned Encouraging to see CMS & Beams Div. Collaborating on project FNAL is a rocking place to work

Acknowledgements I would like to thank Andreas Jansson, Claudio Rivetta, Hogan Nyugen, Jim Zagel, Kwamie Bowie, Dianne Engram, Elliot McCrory, Dr. Davenport and rest of SIST committee. The 2003 SIST summer interns