Detectors Assembly

Strip detectors

Pad detectors

Radiation Monitor for HERA

Correlation with scintillation counter rates

Reaction to the beam currents

The instantaneous count rate can be helpful for the HERA crew as afeedback from the detector during injection and the beam steering:

http://h1lumiserver.desy.de:8080/main/h1mon.html

In coincidence with some other counters the radiation monitor can beused for an automatic beam dump in a case of severe radiation load.

Radiation Background

Dose rate measurement with Pads

Intense background components:

• Synchrotron radiation:

The synchrotron radiation fandoes not enter the H1 facilitydirectly but some part of it scatters from absorbers to-wards the detector and does heat the beam line optics that causes a gas evaporation and worsens the vacuum. In turn this increases a

where the latter is the main background component.

• e-gas scattering• P-gas scattering

The trigger algorithm of the pad detector was extended to monitor online the particle flux through the silicon. The multiplicities of triggered pads are summed up within 1 second, during the next second the result obtained is sent out while the next integral is being prepared.

One silicon sensor (20 cm2)is taken as an area unit forthe radiation monitor. Themaximum rate over 48 paddetector modules is beingdisplayed.

Radiation Monitor for H1

][)(

2cmScountsND

gcmMeV /22

The radiation monitor rate dependson the vacuum in HERA, therefore forthe given conditions the backgroundcan be predicted in the first approxi-mation from the current product:

Measuring the cumulative dosebecomes possible with silicondetectors (besides beam losseswhen the energy is released in avery short time) as all particlesdeposit on average the same energy

A linear correlation between the radiationmonitor rate and the ionization current inthe central trackers is used for chambersto control their “turn on” conditions toprevent their high voltage trips.

epep IIα)αI(PIdt

dN 0

FST and BST Collaboration

Detector Smiths

• DESY Hamburg• Prague Charles University• Institute of Physics AS CR• Rutherford Appleton Laboratory

Max Klein Peter Kostka Thomas NaumannJan Kretzschmar Tomas Lastovicka Mirek NozickaWolfgang Lange Hans Henschel Joachim Meiβner

Rainer Wallny Doris Eckstein Vladimir ArkadovMilan Janata Ulrich Harder Wolfgang EickWolfgang Philipp Olaf Gräber Ilya TsurinSergey Gorbunov Bill Haynes H.-C.S-C.

• DESY Zeuthen

The Backward Silicon Tracker

• 144 strip detectors (number of readout channels = 92.160)

• 48 pad detectors (number of trigger channels = 1536)

Strip detector(640 readout strips)

Pad detector (32 pads)

Detector system

Applications:

• Track curvature measurement and the particle’s momentum determination

• Z-vertex reconstruction and rejection of non-eP tracks and other background

• Track trigger for an efficient use of the high luminosity of HERA-II

Deeply Inelastic Scattering event

BST acceptance in the x, Q2 kinematical plane

DIS Measurements with the BST

Event kinematics:

);2/(sinE

E'1

kP

qPy 2

e

e

);2/(cosE'E4)k'(kqQ 2ee

222

)Q(x,F)Q(x,FQ

2

Qx

)Qσ(x, 2L

2224

2

2

22y

xs

;sy

Qx

2

Inelastic eP-scattering cross-section:

Inclusive measurementsof a scattered electron with a calorimeter and the BST:

The New Radiation-hard Readoutfor the Forward and Backward

Silicon Detectors of H1

I.Tsurin

10th European Symposiumon Semiconductor Detectors

University of Antwerpen,on behalf of DESY

Wildbad KreuthJune 12-16, 2005

Address: Notkestrasse 85,22607 Hamburg, Germany.

Phone: +49-40-8998-4598

E-mail: tsurin@mail.desy.de

Pad Detector Module

PRO/A readout chip

The PRO/A readout chip was designed in collaborationbetween DESY Zeuthen and IDE AS (Oslo, Norway) andmanufactured in 1.2 µm N-well CMOS process by AMS.

Specifications:

• 32 channels with digital and analog outputs with controlled ON / OFF function and internal or external trigger thresholds • Individual mode / subtraction of neighboring channels for the common mode suppression

• Dynamic input range 35±1 dB• Controlled gain 15…30 mV / fC

• ENC (1σ) 600±100 e• Noise slope 15±5 e / pF

• Shaping time constant 30±1 ns• Has a calibration pulse mode

The front-end boards for the detector control and the trigger dataprocessing (ALTERA chip EP20K300E is the core of each board):

Pad Front-end Electronics

• Monitoring the radiation background

• Monitoring the multiplicity of triggered pads

• Manipulating the PRO/A steering codes, setting trigger thresholds• Synchronization of all detector pulses to HERA clock frequency• Track validation with masks and computing of the track topology• Accumulating and transmitting of raw data from the silicon pads

Interface tothe H1 DAQ

96 channels

Auxiliary functions:

• Temperature measurements with a CAN chip.

DetectorModules

384 channels

Heavy Flavor Physics

Acceptance forheavy quarks withthe FST and BSTQ2 ~ (5…400 ) GeV2

cF2measurements (2…10)% in extended x range

bF2measurements withhigh luminosity

The new “Analog Pipeline Chip”

APC128 UMC.25 specifications:

The APC128 readout chip and its decoder were re-designed in collaboration between DESY, PSI (Villigen, Switzerland) and KIP (Heidelberg, Germany) and manufactured in 0.25 um process by UMC (Taiwan).

• 128 channels, each containing an analog pipeline with a depth of 32 storage capacitors• ENC (1σ) 400±100 e (the switching noise has a large contribution)• Shaping time constant 1.5±0.3 µs• Minimum sensitivity 5±1 mV/fC; the signal amplification and processing is possible by sequencer code

Strip Detector Module

The strip pitch = 25 µm, the readout pitch = 75 µm (every third strip has an analog readout). The charge sharing between intermediate and readout stripsallows for a precise coordinate measurement: hit residuals for tracks 10-15 µm.

A serial readout of two detectors (2 x 640) strips with 1 µs / channel requires1.3 ms for the data processing with a continuously cycling acquisition program (sequencer code). The APC settings are reloaded regularly making the readout rather stable against single event upsets.

The old APC128 SACMOS radiation damage studies*

Signal buffering, Clock distribution, Supply regeneration

Front-end functions (less critical to the choice of components):

A cumulative dose above 100 kRad is responsible for the pedestal and hence readout amplitude lowering. This effect is attributed to the bulk leakage currentat the preamplifier's input. The influence of impurities trapped in the silicon ontosignal could be parameterized and investigated in the ASIC design package with an equivalent current source.

* “Development of a radiation hard version of the Analog Pipeline ChipAPC128”, M. Hilgers, R. Horisberger, Nucl. Instr. Meth. NIM A481 (2002)pp. 556-565.

Commercial components preserving generalfunctionality with the total ionizing dose upto 3.2 MRad:

• Field programmable gate arrays (ALTERA): EP20K300EQC240, EP1K30TC144• Fast comparators (MAXIM): MAX964EEE• Opto-couplers (Agilent): HCPL-0731• Low dropout voltage regulators (Nat. Semicond.): LM3965ES, LM2991S, LM1117MP, LM1086CS• Amplifiers (Analog Devices): AD8554AR• Reference (Analog Devices): AD589JR• Differential transmitters / receivers (Texas): AM26LV31CD, AM26LV32CD

Design Outlook

1. Analog circuits should have 100% feedback, i.e. voltage repeaters must be used rather than amplifiers. In any case the digital circuitry is preferable because it operates with two robust levels.

2. As much functionality as possible should be implemented into the program algorithm. It is always easier to recompile the design acti- vating new FPGA resources than to repair the hardware.

3. To ensure a reliable operation in the environment with radiation load a steady HERA background control and a fast response on radiation effects in the silicon are very important to keep the exposure rate below 10 kRad/year.

Operation experience:

The online Trigger Software

Single event latch-up can freeze data bits distorting the trigger patterns. A self-latch scheme for input signals with a common reset is utilized to avoid combinations with permanent "1". Mask permutations are written to compensate for stuck signals or inefficient pads.

Single event upset may force a trigger signal. The coincidence with other H1 sub-detectors (SPACAL, Veto counters etc.) reduces a risk of a false trigger. All signal conditions and relations are synchronized to the clock frequency to protect the trigger algorithm against random data changes .

Soft failures are resolved by the front-end reinitializing

Memory bit flips were crucial for the frequent trigger masks, therefore the predefined track patterns were coded as combinatorial logics.

* “Plasma-charging damage in ultra-thin gate oxide”, Kin P. Cheung, Microelectronics Reliability 40 (2000), pp. 1981-1986.

Preamplifier’s Circuitry

P-FET transistors enclosed inthe N-well are better isolatedfrom the P-substrate leakagecurrents. Their usage in thepreamplifier’s feedback cir-cuitry requires negative biasvoltages with respect to thesignal ground.

To prevent high stress currentdensity during plasma exposurethe gate voltage must be alwaysabove the substrate potential *

Ring-shaped P-FET from the “PSI_025V2_core” library

The signal ground is separated from the substrate and the operating (.)of the push-pull cascade is shifted by +0.6 V. Now the gate voltage of the feedback transistors could be selected in the range (0…+0.6) V.