DØ Radmon statusDØ Radmon status 26/08/9926/08/99

Sijbrand de Jong/Bram Wijngaarden/Silke DuensingSijbrand de Jong/Bram Wijngaarden/Silke Duensing

Contents:Contents:What is to be monitored and what actions to take What is to be monitored and what actions to take ??Historical setting: CDF and OPALHistorical setting: CDF and OPALThe solutions chosenThe solutions chosenStatus of preparationStatus of preparationTime tableTime tableSummary and OutlookSummary and Outlook

What is to be monitored:What is to be monitored: Instantaneous radiation levels:

at millisecond time scales

at seconds time scale

at minutes time scale

at days/months/years time scale

Sensitivity:

rad/hour (long term)

rad/second (short term/bursts)

Action: Beam abortAction: Beam abort High Instantaneous radiation levels:

at millisecond-seconds time scales

rad/second levels

Integrate the radiation with a running few seconds integration time and fast rise time (allow abort as fast as in 1 millisecond if the times get rough)

Absolute reliability: implement in hardware and failsafe, also reliable monitoring (to test reliability and to justify a posteriori)

History part I: CDFHistory part I: CDFCDF already has a monitor and beam abort

system:

Beam Loss Monitors (BLMs):

1 Atm. Ar filled glass/Al tubes

Current Radiation / low sensitivity

TLDs infrequent access at long intervals

Used to gauge the BLMs a posteriori

Will use same system in RUN II, but at larger z distance (and the distance was already large…)

History part I: CDFHistory part I: CDFDØDØBLM proven to be reliable, Beams division

trusts them … use them also for DØ

Bulky: use at large z distance, 4 on each side of DØ I.P.

Drawbacks:

At large distance from point of interest (SMD)

Limited sensitivity: no low dose / long term integral

But:

Can use for beam abort (only low sensitivity needed, trusted by beams division)

Gauge with a second sensitive system near

SMD::

StatusStatusBLMs available/delivered from Beams division

The mounting of the tubes in principle decided (the drawing has to be cleaned up, then production can start)

HV and signal cables per (long) coax cables (5 cables per side: 1 HV (4 tubes daisy-chained) and 4 signal cables)

History part II: OPALHistory part II: OPALAll 4 LEP experiments have good radiation

monitoring and beam abort systems, the OPAL system is used as inspiration for DØ.

Principle: ~1 cm2 Si diode current radiation

Two gain ranges (a la OPAL) to accommodate high sensitivity fast measurement and lower sensitivity long term integral measurement

Maintain fast signals to the external electronics

Location of the sensors in DØ:

F-disk H-disk

The sensor modulesThe sensor modules

Sensor module description Sensor module description IIWedge-shaped modules of flex print laminated

onto thin Beryllium support/cooling plates

Mount on F- & H-disk support rings between wedges

Flex print ends in flex cable that feeds through the CF support tube (F-disk) and connects to traditional cable bundle using a small PCB with an Hirose connector The unshielded cable part is to be kept as short as possible

Be plates keep Si diodes significantly colder than the strip detectors

Sensor module description Sensor module description IIIIPre-amp electronics with two gains to be

transmitted to the outside world

Rad hard electronics

Low power dissipation

Fast signal, allowing to capture single beam crossings if desired (this is not really foreseen in the standard mode of operation, but can be quite useful to calibrate the system using single MIPs)

Choice of dynamic rangeChoice of dynamic rangeThe design allows to change the dynamic

range, within reasonable limits, by changing one or two discrete (smd) components

Current choice: Low gain 3 V 400 Rad/second

High gain 3 V 225 Rad/hour (These are sustained voltages-rates)

The rise- and shaping-time are fixed. The shaping-time is a few hundred ns, the rise-time much faster

More design choicesMore design choicesA leakage current compensation can be set

externally (remotely)

The circuit is tested to 400 V bias voltage and is protected against a short over the Si diode(s)

StatusStatusSensor module prototyped and final circuit decided

Be plates dimensions fixed and ordered F-disk H-diskwidth at top 0.866”/22mm 0.866”/22mmwidth at bottom 0.394”/10mm 0.472”/12mmtotal length 4.082”/103.68mm

4.496”/114.2mmtop part length 1.535”/39mm 1.535”/39mm

Flex circuit order pending understanding of the length of the flex cable part (distance of connector from the circuit)

Si diodes sensor module Si diodes sensor module prototypeprototypeCorrect dimensions for F-disk

2 layouts tested (one better than other: choice made)

Design allows to cover with EM shielding foil

Si diodesSi diodesTest structure from H-disk wafers

48 diodes with and 48 diodes without guard ring in hand

setting up I-V, C-V (depletion voltage) and leakage current tests at University of Nijmegen select the best for mounting on modules

CablingCabling BLMs: coax cables all the way to receiver

electronics. Need a break at the end of the muon shield.

Diodes: short flex cable, then “round” cable to patch panel between barrel and end cap CAL, then more robust round cables to receiver electronics. Signal as fine group shielded twisted pair and power cables bundled together with common electrical and mechanical shield.

Cabling: open questionsCabling: open questions Lengths of flex cable ?

Length of conventional cable parts ?

Types of conventional cables that may be used (safety/”standard cable”/…) ?

Patch panels: available size/… ?

Location of receiver electronics ?

ReadoutReadoutVME based (single crate system) using analog

receiver, integrator boards, one or more ADC modules and a VME CPU/host

Use Beam division/CDF logarithmic receiver/amplifier for BLMs, use also their scheme to derive beam abort signal

Use linear differential receivers a la OPAL for Si diodes, use parallel streams with different integration time

Readout Readout (continued)(continued)

Use cyclic buffer for fast readout (0.1-1ms) and read out on demand (beam abort/warning level/test/…)

Send integrated rates (Rad/sec or Rad/hour) with averages over several seconds-minute to display in control room, store these values once per minute in data base

Keep this one VME crate on uninterruptable power or connect to Tevatron power

Make sure this crates functions independently from DØ readout/slow controls and monitoring

Readout: open questionsReadout: open questions ”Standard” DØ VME ADC module ?

”Standard” DØ VME CPU module ?

”Standard” DØ online data base ?

Connection to DØ slow control and monitoring system ?

Presentation in DØ control room ?

Interface to Tevatron (beam abort/monitoring info) ?

Tevatron startupTevatron startupAt Tevatron startup (without DØ) provide fully

functional system

Test the system

Feed-back information to Tevatron

The Si diode sensor modules will be in addition to those installed on the SMD (made as normal PCB)

Temporary mounting/support system for BLMs and Si diode sensor modules still to be designed

Schedule (1999-2000)Schedule (1999-2000)Mid-Sept: Final layout of Si diode sensor modules Final design of BLM support systemEnd-Sept: Final design of temporary supportEnd-Oct: Final design of receiver module electronics Order VME crate, ADC and CPU modules Final and temporary BLM support finishedEnd-Nov: Si diode sensor modules finished (2 sets)End-Dec: Receiver electronics finished (+VME ADC/CPU)

End-Jan: Fully functional system around beam line Si diode sensors ready for mounting on F- and H-disk support rings

SummarySummaryTwo complementary radiation monitoring systems

BLMs in hand, mounting design ~completed, manufacturing no problem (at Univ. of Nijmegen)

Design of Si front end done and prototyped

Design of readout electronics ongoing for both systems (but no particular difficulties foreseen)

Work needed on: cabling, interface to DØ and Tevatron

Separate system foreseen at Tevatron set-up