D

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DØ Radmon status 26/08/99Sijbrand de
Jong/Bram Wijngaarden/Silke DuensingContents?W
hat is to be monitored and what actions to take
??Historical setting CDF and OPAL?The
solutions chosen?Status of preparation?Time
table?Summary and Outlook
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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)

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Action 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)

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History part I CDF

• CDF 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)

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History part I CDF?DØ

• BLM 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.
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• 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

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Status
BLMs 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)
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History part II OPAL

• All 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

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• Location of the sensors in DØ
• F-disk
  H-disk

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The sensor modules
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Sensor module description I
Wedge-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
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Sensor module description II
Pre-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)
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Choice of dynamic range
The 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
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More design choices
A 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)
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Status
Sensor module prototyped and final circuit
decided Be plates dimensions fixed and ordered
F-disk
H-disk width at top 0.866/22mm
0.866/22mm width at bottom 0.394/10mm
0.472/12mm total length 4.082/103.68mm
4.496/114.2mm top 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)
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Si diodes sensor module prototype
Correct dimensions for F-disk 2 layouts
tested (one better than other choice
made) Design allows to cover with EM shielding
foil
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Si diodes
Test 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
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Cabling
? 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.
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Cabling 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 ?
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Readout
?VME 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
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Readout (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
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Readout 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) ?
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Tevatron startup
At 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
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Schedule (1999-2000)
Mid-Sept Final layout of Si diode sensor
modules Final design of BLM
support system End-Sept Final design of
temporary support End-Oct Final design of
receiver module electronics
Order VME crate, ADC and CPU modules
Final and temporary BLM support
finished End-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
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Summary
Two 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