COMET UH M E P COMET Comments Readout

COMET UH M E P COMET Comments --Readout for the COMET e Tracker With special THANKS to my sponsors of this talk Satoshi Mihara Manobu Tanaka Masaharu Aoki 6/9/1010 Ed Hungerford University of Houston (for the COMET Collaboration) Ed Hungerford 1

COMET UH M E P Introduction to COMET • COMET (Phase I) is a search for coherent, neutrino-less conversion of muons to electron (μ-e conversion) at a single event sensitivity of 0. 5 x 10 -16 • The experiment offers a powerful probe for new physics beyond the Standard Model. • COMET will be undertaken at J-PARC. Phase I (COMET) uses a slow-extracted, bunched 8 Ge. V proton beam from the J -PARC main ring. • A proposal was submit to J-PARC Dec. 2007, and a Conceptual Design Report submitted June 2009. COMET now has Stage-1 approval from the J-PARC PAC (July 2009), and is completing R&D for the TDR. 6/9/1010 Ed Hungerford 2

UH M E P Design Considerations for COMET (and generally all high precision COMET measurements of zero) • Electron Resolution Minimal Detector Material – Thin, Low Z Vacuum Environment REDUNDENT measurements of the electron track • Rates Up to 500 k. HZ single rates Large channel count R/O timing (~1 ns) and analog information • Dynamic Range Protons 30 -40 times Eloss for MIP Pileup and saturation Maintain MIP track efficiency • Low-Power, Low-foot print electronics Heat Signal Transmission through the vacuum walls Noise • Robust measurements • REDUNDANCY (Redundancy, Redundancy) Ambiguous hits, dead channels, accidentals Ed Hungerford Reconstruction of ghost 05 -30 -09 for thetracks COMET collaboration 3

UH M E P COMET μ→eγ and μ-e Conversion COMET • eg • μ-e conversion Background Challenge Beam Intensity accidentals gamma resolution limited beam e resolution reconstruction Less limited • μ→eγ : Accidental background is given by (rate)2. To push sensitivity the detector resolutions and timing must be improved. However, (in particular photon detection) it would be hard to do better than MEG. The ultimate sensitivity of MEG is about 10 -14 (with a run of 108/sec). • μ e conversion : Improvement of a muon beam is possible, both in purity (no pions) and in intensity (muon collider R&D). Higher beam intensity can be used with present timing technology because no coincidence is required. 6/9/1010 Ed Hungerford 4

COMET UH M E P COMET at J-PARC Pulsed Proton Beam p Source B( + Al) e + Al <10 -16 Transport 5 m 6/9/1010 target electron Transport Detection • Modification of MECO/MELC • Requires slow extracted, pulsed beam ~8 Ge. V Ed Hungerford • Mu 2 e at FNAL is another MECO resurrection 5

COMET UH M E P Target and Detector Solenoids COMET 6/9/1010 Ed Hungerford 6

UH M E P COMET Comparison to MECO COMET • Proton Target - tungsten (MECO) - graphite (J-PARC) • Muon Transport MECO - Magnetic fields and solenoids are different. - Efficiency of the muon transport is equivalent • Spectrometer - 1011 stopping muons/sec -Straight Solenoid (MECO) >500 k. Hz/wire - Curved (COMET) ~1 k. Hz /wire • Planer Tracker 6/9/1010 Ed Hungerford 7

COMET UH M E P COMET Tracker and Calorimeter Background COMET Total Tracker Rates/plane 6/9/1010 Ed Hungerford 600 k. Hz 8

Muon-to-Electron (μ-e) Conversion Lepton Flavor Violation UH M E E P P COMET Lepton Flavor Changes by one unit μ Decay in Orbit (DIO) μ- → e - ν ν nucleus Coherent Conversion μ - + A → e -+ A m- Nuclear Capture μ- + A →ν+ [N +(A-1)] 6/9/1010 Ed Hungerford 9

UH M E P COMET Background Rejection (~107 s) (preliminary) Backgrounds Events Comments Muon decay in orbit Radiative muon capture (1) Muon capture with neutron emission Muon capture with charged particle emission 0. 05 230 ke. V resolution <0. 001 Radiative pion capture* Radiative pion capture Muon decay in flight* (2) Pion decay in flight* Beam electrons* Neutron induced* Antiproton induced 0. 12 0. 002 <0. 001 0. 08 0. 024 0. 007 Cosmic-ray induced (3) Pattern recognition errors 0. 10 10 -4 veto efficiency <0. 001 Total • 6/9/1010 prompt late arriving pions for high energy neutrons for 8 Ge. V protons 0. 4 • Ed Hungerford • 10

COMET UH M E P Tracking Array 5 Planes – 4 Arrays per plane Each plane arranged in an x, x’, y, y’ geometry of arrays Each array composed of 13 straw units of 16, 5 mm diameter straws Mounted double-array Unit • 16 straws/unit • 208 straws/array • 832 straws/plane • 4160 straws/detector 1. 2 m 6/9/1010 Ed Hungerford 11

COMET UH M E P Manifold COMET 6/9/1010 Ed Hungerford 12

COMET Flex Ribbon Cable through Manifold to FEB Fused HV 15 ns LRC Filter/channel 6/9/1010 Ed Hungerford 13 UH M E P

UH M E P COMET Readout Architecture COMET • On-Detector amplification and digitizing – events passed by optical fiber in serial to an external DAQ (Parallel transfer is also possible) • Electronics based on CMOS to conserve space and power (<65 Mw/ch) – radiation damage is not a problem • Mounted on the detector frame • A (MECO) system has been previously prototyped and demonstrated • COMET Data rates are reasonable 6/9/1010 14

UH M E P COMET Tracker FE Organization Straw Tubes Number of Straws Readout (TDC) Readout (ADC) Per Array (13 x 16) 208 208 Per Plane (4 Array) 832 832 Per Detector 5 Planes (MECO 18) 4160 COMET Manifold (unit) Array Plane Detector PA(16) 1 13 52 260 Digitizer(16) 1 13 52 260 1/4 1 5 1/5 1 ROC Module Controller Assuming: 60 -125 MHz clock and 10 -20 clock ticks for an event (160 ns) (10 -20+ 11) x 4 x 5 x 1. 5 words for an event and 16 bits for a word 1 k/s event rate The total data rate is ~10 -15 Mb/s. Edwith zero suppression 6/9/1010 Hungerford 15

COMET UH M E P An Example The MECO Readout Architecture COMET From Anode Wire Separated PA And Digitizer Sequencer Plane ID for readout To External DAQ 6/9/1010 Ed Hungerford 16

UH M E P COMET MECO Prototype COMET FEATURES • The number of data transfer lines is 24 (16 data + 6 control) • A system clock is regenerated by the local buss sequencer • A trigger input is associated with readout units • A trigger reset counter determines the data time stamp • A system reset to return to standard operating conditions • A slow control buss for control and monitoring • Low voltage power of +3. 3 V(300 A) and -3. 3 V (100 A) • Total Power < 1. 8 k. W (PA and Digitizer only) • 05 -30 -09 6/9/1010 • Ed Hungerford for the COMET collaboration • 17

COMET UH M E P Drift Simulation Position Along Y (cm) COMET Trajectory Wire 6/9/1010 Gas – 80 %CF 4/20% C 6 H 10 Velocity - 8. 5 cm/μs Drift Time - 45 ns Ed Hungerford 18

UH M E P COMET Measurements and Simulations COMET Simulated Anode signal Simulated Charge 15 ns Filter 6/9/1010 Ed Hungerford 19

COMET UH M E P The MECO Prototyped System • COMET A front-end board was developed to • The Digitizing Board layout is test the ASD-4 and a driver board is completed, tested, and the used to adapt the LVDS output to our digitizing ASIC designed. lab CAMAC TDC. Digitizing Boards FEB Board Connected by flex cable Mother Board with FPGA Memory and PCI controller 6/9/1010 Ed Hungerford 20 Elefant Chips (2 x 8 channels)

UH M E P COMET 32 Channel MECO Prototype COMET 6/9/1010 Ed Hungerford 21

COMET 6/9/1010 UH M E P Specifications for COMET ASIC preamp Parameter Name Value Note Polarity Bipolar Positive input for Colorimeter Channel number 16 Cover 8 cm with 5 -mm straws Linear range <60 f. C Input capacitance 20 p. F Equivalent Noise Charge 0. 5 f. C Peaking time 100 ns Coupling AC Timing resolution <2 ns Power consumption <5 m. W/ch Test input Yes Ed Hungerford Amplitude measurement (250 -ns signal width) 22

COMET UH M E P ASIC Digitizer • Digitizer ASIC Design based on the ELEFANT ASIC used in BABAR (8 channels/ASIC) Work in collaboration with design engineers at LBL Rescale ASIC to 0. 25 m technology and 3. 2 V interfaces Solves identified problems with the ELEFANT design Change clock frequency (20 -60 Mhz) Change from waveform sampling to time-slice integration Increase ADC bits to 10 COMET • ~5 s Latency, self or external trigger • Power Consumption 65 m. W/channel (Total Power 1, 650 W) Design (LBL Engineer) $518 K; Fabrication (2 prototypes) 2 x $45 k; Preproduction samples $50 k; Production and packaging $231 k, Testing $42 k => $931 k + 37% contingency Several more modern Waveform (ADC Sampling) ASICS designs e. g. Belle, PSI designs, ATLAS, etc 6/9/1010 are Possible for COMET --Ed Hungerford 23

Digital chip Redesign COMET • Benefits: reduce noise, simplify the system design, better technology, lower power consumption, lower system cost. Prediction of the production cost is ~$8 -15 per channel. UH M E P

UH M E P MECO Digitizer chip specs COMET Items Upgraded Digitizer Channel per Chip 8 System Input Clock PLL System Clock Divider System Frequency 7. 5~15 MHz sine wave differential 4 2 1 30~60 MHz 15~30 MHz 7. 5~15 MHz ADC sampling Clock ADC Resolution System Clock 8 bits 9 bits ADC Implementation Pipeline ADC TDC DLL (PLL) Clock 30~60 MHz (PLL divided Clock) TDC resolution TDC Width (combine with PLL) 0. 26 to 0. 52 ns LSB 6 bits TDC Implementation Noise performance 6/9/1010 10 bits 7 bits 8 bits DLL (PLL) Digital feed back to the analog channel less than 0. 5 LSB Ed Hungerford 25

UH M E P Elefant II ASIC COMET Time and amplitude samples stored together in a latency pipeline 6/9/1010 Ed Hungerford 26

UH M E P A More Modern Design CDC – Belle Central Drift Chamber COMET 6/9/1010 Ed Hungerford 27

Other Examples Readout of ATLAS TRT • Based on two ASICs: front-end + digitization • ASDBLR – Front-end, 8 -ch – Separate preamps • Track detection • TR photon detection – Ternary outputs • DTMROC – Digitization, 16 -ch – TDC + FIFO + Serialization – Each beam bunch has one slice in FIFO – Control and thresholds to ASDBLR • Power consumption: 40 m. W/ch COMET UH M E P

UH M E P ROC Board Design To FE Board COMET • • • Each ROC has a FPGA to control the readout sequence from the Elefant II chips. Data are stored on the board temporarily in the dual-port RAM. Configurations, like the number of channels connected to this board, readout mode (sparse mode, zero-suppression mode, etc. ), are configured through the I 2 C bus. 6/9/1010 CONN. High Speed Serial Bus I 2 C Dual Port FPGA CPLD I 2 C RJ-11 Virtex-II pro Clock Trigger Reset Distribution RJ-45 Ed Hungerford RAM PROM V 3. 3 REG Transmitter RJ-45 V 2. 5 REG Pwr Conn. 29

UH M E P Fast Control Signal COMET • Reset, Trigger, and Reference clock are provided by DAQ system (Trigger and Fast Control Fan-out ). • These are transmitted as differential signals (LVDS). • Reference clock is 10 MHz with reasonable jitter. On the module controller or ROC, this clock frequency will be divided by PLL to the sampling frequency (40 -60 MHz) with much smaller jitter (~200 ps) to satisfy ADC requirement. • Event numbers are embedded in the trigger signal (real time trigger signal followed with the number). • The Control module feeds the fast control signal to each ROC Box through 4 pairs low skew differential, shielded cable. No matter how far the ROC is from the module controller, all these Fast Control lines must have the same length to reduce the time skew. This will also ensure the timing accuracy for the whole system. 6/9/1010 Ed Hungerford 30

UH M E P Data Transfer • Data transfer from ROC to the module controller uses shielded twisted pair cable (low skew <150 ps /10 m). • From the module controller, data passes feedthrough to the Event Builder of DAQ: differential copper wire or optic fiber. • Differential copper wire: • Easy to install from the vacuum wall. • Can be 100 Mb/s (CAT-5 e) or 200 Mb/s (CAT-6). Up to 100 m • Full bandwidth is not used due to protocols (handshaking). • Cheaper. • Optic fiber: • Penetrations through the vacuum wall? Hermetic feed through exits. No engineering experience. • Fast. Can be ~Gb/s. ~km long. • Radiation hardness of the transceiver should be considered. • Costs more. COMET 6/9/1010 Ed Hungerford 31

UH M E P Data Package to the Event Builder COMETSquencer Header ROC Header FE Header Channel Header 31 28 27 25 24 23 22 20 19 0 0000 Sequencer ID 12 11 Event ID 0010 ROC ID Event ID 0100 FE ID Event ID 0110 Channel ID Event ID Data 0111 Data 0 Data 1 Data 0111 Data. . . Data 0111 Data n-2 Data n-1 Channel Trailer 1110 Channel ID DWord Length Event ID Repeat Channels FE Trailer 1 1100 FE ID Event ID FE Trailer 2 1101 FE ID DWord Length Repeat FEs ROC Trailer 1 1010 ROC ID Event ID ROC Trailer 1 1011 ROC ID DWord Length Repeat ROCs Sequencer Trailer 1 1000 Sequencer ID Sequencer Trailer 2 1001 Sequencer ID 6/9/1010 Ed Hungerford Event ID DWord Length 32

2 nd Coordinate Readout COMET Tracking with multiple hits in the detector planes can produce ghost trajectories. A 2 nd readout might reduce ambiguities. Possible Methods of 2 nd Coordinate Measurements in Wire Detectors 1) Induction on the cathode a) Strips (pads) b) Delay lines parallel to the anode wires 2) Anode readout a) Charge division on a resistive anode (NIM A 479(02)591) or Cathode b) Signal timing between the straw ends c) Signal rise time UH M E P

UH M E P Charge Division Readout (IEEE 42(95)1430) COMET L/L ~0. 6% Signal Division

Charge Division Issues COMET Charge division might provide a 2 nd coordinate readout with resolution on the order of L/L 1%; BUT 1) The resolution deteriorates with background rate 2) Reducing the integration gate, implementing base line restoration reduces the collected charge (resolution) 3) Maintaining calibration requires special data runs and pulser inputs (automated) 4) Careful design of all electronics to reduce noise and termination of lines (frequency dependence) 5) Precision wire resistance and analog preamp 6) Shaping amp is a compromise between noise reduction (very sensitive) and rate handling 5) Both ADC and TDC readout 7) Charge integration within a time gate UH M E P

Delay Line Readout NIM A 479(02)591 COMET L = 6. 5 mm 1. 7 m long drift-cell UH M E P

Straw Delay Line UH M E P COMET ~1 m straw delay line is presently under construction Strip width is 1 mm spaced by 1 mm Expected time delay for 1 m is 45 ns one-way. Differential readout to remove common mode propagation

Delay Line Issues COMET Delay Line Timing might provide a 2 nd coordinate readout with resolution on the order of L ~ 5 mm. The time sum equals propagation delay + drift time, better signal stability, and anode wire hit ID’ed. BUT 1) Requires additional material 2) More difficult to construct 3) More electronics to build and install in a limited space 4) Capacitive and inductive coupling between channels 5) Careful electronic design 6) Calibration UH M E P

UH M E P COMET Summary COMET • COMET is a Phase I search for coherent, neutrino-less conversion of muons to electron (μ-e conversion) at a single event sensitivity of 10 -16 • The experiment offers a powerful probe for new physics beyond the Standard Model. • The experiment will be undertaken at the J-PARC NP Hall using a slowly-extracted, bunched proton beam from the J-PARC main ring. • The Experiment is developing a TDR and refining design details. The experiment has completed a CDR and has Stage-1 approval of the JPARC PAC. • The electronic readout of the tracker (and calorimeter) is challenging, requiring new ASIC development that have low power, excellent timing, reasonable resolution, and rate handling, and are robust. • The system design requires on detector digitization, storage, buffering, and latency. • The event builder must reconstruct events from asynchronous buffer reads • We need expert engineering experience with the technical designs 6/9/1010 Ed Hungerford 39