TEVATRON IONIZATION PROFILE MONITOR Andreas Jansson Fermilab

11/11/2004Tevatron Ionization Profile MonitorA. Jansson 2 People AD: C. Rivetta L. Valerio J. Zagel B. Dysert C. Lundberg … CD: M. Bowden R. Kwarciany D. Slimmer … PD: A.Bross K. Bowie H. Nguyen T. Fitzpatrick … Also help from: D. Harding (TD), V. Kashikin (TD), T. Zimmerman (PD), Z. Tang (PD), B. Hively (AD), the Tev Techs …

11/11/2004Tevatron Ionization Profile MonitorA. Jansson 3 Talk outline Motivation for IPMs in Tevatron Special challenges in Tevatron Design of Tevatron IPMs Tests Pictures from “down under”.

11/11/2004Tevatron Ionization Profile MonitorA. Jansson 4 Motivation Directly measure injection matching and emittance growth at injection Continuously measure emittance eg on ramp

11/11/2004Tevatron Ionization Profile MonitorA. Jansson 5 IPM working principle Measure distribution of rest gas ionization by: –Drifting ions onto a detector using an electric field, or –Drifting ionization electrons onto a detector using a E||B field.

11/11/2004Tevatron Ionization Profile MonitorA. Jansson 6 Challenge I – Small beam size Small beam size -> fine detector granularity (1/4 mm pitch) Three different positions due to helix -> need wide active area (~3 cm) Many channels (128)

11/11/2004Tevatron Ionization Profile MonitorA. Jansson 7 Challenge II – Two beams  = 20  mm mrad  p/p = X [mm] Y [mm] Inj. old helix Inj. new helix Flattop One and three sigma contours Projected beam profiles may overlap Don’t trust to separate beams Separate by timing -> single bunch resolution!

11/11/2004Tevatron Ionization Profile MonitorA. Jansson 8 Challenge III – Too good vaccum Gas pressure at E0 before 2004 shutdown was in low ’s, slated to be improved Based on estimated gas composition (RGA scan), expect about 1000e/bunch for a 10cm detector at Torr and protons/bunch. Need for a local vacuum bump after vacuum inprovements. graph: F. Sauli, CERN 77-09

11/11/2004Tevatron Ionization Profile MonitorA. Jansson 9 Challenge IV – Parasitic signals Measure extremely small signal (~fC) in the presence of very strong EM field from beam. Anode strip acts as electrostatic pick-up. Sharp resonaces require strong LP filtering, low time resolution. Beam to anode strip coupling measured on Booster IPM.

11/11/2004Tevatron Ionization Profile MonitorA. Jansson 10 Fermilab QIE8 ASIC Charge Integrating Encoder (QIE) Developed at Fermilab Used by KTeV, CDF, Minos, CMS… Frequency range 7-53 MHz No deadtime. LSB 2.6fC (16000e) in logarithmic mode, 0.9fC (6000e) in linear mode Dynamic range >10 4 in logarithmic mode Can achieve noise of O(1fC) Radiation “tolerant” design: T. Zimmerman

11/11/2004Tevatron Ionization Profile MonitorA. Jansson 11 QIE simulations Injection is most difficult (fewer counts per channel). Signal per bunch is small, but gain limited by MCP saturation effects from total (proton) signal. Need about 300 primaries (per bunch) for 10% beam width accuracy (requires gas injection). Higher accuracy can be obtained by averaging many turns (ramp measurement). simulations: H. Nguyen

11/11/2004Tevatron Ionization Profile MonitorA. Jansson 12 Keeping the noise low To keep noise at minimum, digitize close to source (in tunnel). 128 channels  1 byte  15 MHz = 16 Gbit/s of data! Use high-speed serial links (on optical fiber)

11/11/2004Tevatron Ionization Profile MonitorA. Jansson 13 QIE test stand Using laser based PMT test setup in Lab6 KTeV test board modified with CMS- QIE Observed good linearity and insensitivity to clock phase measurement: H. Nguyen

11/11/2004Tevatron Ionization Profile MonitorA. Jansson 14 QIE quirks QIE input is NOT bipolar! Relatively mall pulse of wrong polarity can temporarily shut down the input –Beam EM pick-up yield bipolar pulses –Cable reflections may invert pulse polarity Limit diffuse, need to be careful

11/11/2004Tevatron Ionization Profile MonitorA. Jansson 15 Cable tests Stepping QIE clock phase w.r.t the incoming pulse, can improve time resolution Derivation of composite signal yields the original pulse Used to study reflections due to connectors in front-end cabling measurement: C. Rivetta

11/11/2004Tevatron Ionization Profile MonitorA. Jansson 16 Rad level measurements Reading 125 mrad/h during normal running at ~4.5 feet 18 years to 20 krad!

11/11/2004Tevatron Ionization Profile MonitorA. Jansson 17 Component rad tests Tested commercial TI serializer in Tevatron tunnel for >200 days. Previously tested (by others) for total dose ~Mrad. Only handful of link errors seen. One latchup candidate, cleared by cycling power. Observed error rate should not affect operation.

11/11/2004Tevatron Ionization Profile MonitorA. Jansson 18 MCP saturation MCP output current per unit area is limited by MCP pore recharge time. If hit rate per pore exceeds recharge time, output is reduced Onset of saturation observed in MI IPMs, as expected from calculations.  For Tev, will abandon Chevron configuration since extra gain can not be utilized (allows to run at higher bias). Turn # measurement: L. Short Bull

11/11/2004Tevatron Ionization Profile MonitorA. Jansson 19 MCP test stand Built to measure eg gain depletion of used MCPs, and as a test bed for new systems (eg Tev IPM). photo: A. Bross measurement: B Dysert

11/11/2004Tevatron Ionization Profile MonitorA. Jansson 20 Detector design Based on MI eIPM prototype –Flange-mounted detector for quick installation Many modifications –Better screening –Different voltage profile –Provisions for calibration device

11/11/2004Tevatron Ionization Profile MonitorA. Jansson 21 Beam EM screening Enclose anode board and signal cabling in Faraday cage! Wire mesh over MCP lets (most) electrons thru Avoid signal cable mismatch as far as possible 10kV 1kV GND MI, Booster Tev

11/11/2004Tevatron Ionization Profile MonitorA. Jansson 22 Anode board ¼ mm strip pitch 200 channels (128 instrumented) Provision for on-board LP filter/ back- termination (series resistor) Connected to feedtru by UHV compatible 50Ω flex-circuits High resolution area can be moved by swapping connectors artwork: C. Lundberg

11/11/2004Tevatron Ionization Profile MonitorA. Jansson 23 Beam based alignment Due to high strip aspect ratio (400:1), good alignment with beam is required. Motorized detector stands allows for beam- based elimination of any relative angle Translation is also possible, to scan active area on MCP graph: K. O’Brien

11/11/2004Tevatron Ionization Profile MonitorA. Jansson 24 Magnets Single corrector (two- bump) for simplicity. Electromagnets chosen. Can be turned off to verify effect on measurement and machine. Bought from outside manufacturer. design & photo: Scanditronix Magnet

11/11/2004Tevatron Ionization Profile MonitorA. Jansson 25 Tracking – transverse displacement Ionization electrons simulated in B=0.2T, E=100kV/m. Transverse spread from electron momentum less than ¼mm pitch Small space-charge effect seen for protons at flat-top.

11/11/2004Tevatron Ionization Profile MonitorA. Jansson 26 Field quality Longitudinally, E-field is not perfect E×B component produces a small transverse drift velocity To first order, this generates a rotation of the beam “image”, which is removed by beam-based alignment Higher order terms distort the beam image, expect order ~30 nm rms effect on beam size.

11/11/2004Tevatron Ionization Profile MonitorA. Jansson 27 DAQ system CMS-QIE front end in tunnel. Serial data uplink on optical fiber Receiver and data buffer in upstairs PC Timing + clock + QIE settings supplied from PC thru cat-5E cable Timing card (PCI) Timing fanout QIE cards (16x 8 ch) Data Buffer (2*8 ch) (PCI) Host PC (LabView)

11/11/2004Tevatron Ionization Profile MonitorA. Jansson 28 Timing card Produces the 15MHz (2/7 RF) FE clock Decodes and transmits beamsync clock (p & pbar) injection events Transmits QIE settings Separate version of card will decode TCLK/MDAT design & photos: T. Fitzpatrick

11/11/2004Tevatron Ionization Profile MonitorA. Jansson ns (21 buckets) p-pbar separation RF 2/7 1/7 Timing scheme

11/11/2004Tevatron Ionization Profile MonitorA. Jansson 30 Front end card 8 channels (CMS QIE) per board. Data is serialized by CERN GOL ASIC (rad hard) and sent thru fiber Timing fanout board cleans up and distributes clock and timing signals timing fanout QIE card design & photos: K. Bowie

11/11/2004Tevatron Ionization Profile MonitorA. Jansson 31 Data buffer card Handles 8 incoming optical channels Data stored in on- board RAM Read out thru 64 bit PCI bus Doubles as BTeV L1 data buffer prototype. design & photo: R. Kwarciany

11/11/2004Tevatron Ionization Profile MonitorA. Jansson 32 Differential pumping scheme ion pump gauge sector valve sector valve orifice vert ipm horz ipm Calibrated leak N2N2 ion pump sector valve ion pump TSP shut-off valve

11/11/2004Tevatron Ionization Profile MonitorA. Jansson 33 Simulated pressure profile Opening leak valve raises pressure by two orders of magnitude. simulation: A. Chen

11/11/2004Tevatron Ionization Profile MonitorA. Jansson 34 Controlled N 2 leak tests at E4R Red traces: IP and IG in leak chamber Green, Blue and Cyan: IPs and IG in main chamber 6 hours 3 decades leak on test setup: S. McCormick

11/11/2004Tevatron Ionization Profile MonitorA. Jansson 35 Tunnel installation Detector goes here!

11/11/2004Tevatron Ionization Profile MonitorA. Jansson 36 Conclusions and outlook Tevatron IPM project well advanced All infrastructure installed this shutdown. Detector unfortunately not installed need a few days downtime (for vacuum bake).