NA62 Kaon Tagger DCS User Requirements
Tim Jones (tim.jones@cern.ch)
December 2011
Purpose
This note defines the DCS user requirements for the Kaon Tagger (KTAG) for the NA62 Experiment. The Kaon Tagger
(KTAG) is formed of the CEDAR Cerenkov counter and the PMT arrays which collect the light emerging from it. The
KTAG will be used to tag K+ mesons which form 6% of the beam flux through the NA62 experiment.
General Description of the Kaon Tagger
In order to tag the K+ mesons the KTAG must efficiently collect the Cerenkov light produced in the CEDAR. The light
emerges through eight quartz windows distributed uniformly around the beam axis. For each octant the light is
reflected off a spherical mirror and then onto detectors formed from a light-cone array and associated photomultipliers. The primary components of the system are:







CEDAR Cerenkov counter filled with radiator gas (H2 or N2)
KTAG Support Cylinder
KTAG Mirror support cylinder, 8 mirrors and 8 focussing lenses
Two mirror-symmetric KTAG sub-systems (KTAG_JURA, KTAG_SALV) each comprising four 64-channel PMT
arrays, together with their associated electronics and cooling systems, all housed in a single mechanical
support structure and surrounded by a gas- and light-tight thermal enclosure.
KTAG cooling system (1)
KTAG N2 gas system (1)
KTAG HV system(1)
KTAG NINO LV system(1)
The DCS system is required to be able to control the state of the LV supplies to the NINO boards and the HV
supplies to the PMTs as required by the NA62 run control system. In addition, a number of sensors will be
monitored to check the operational status of the KTAG (eg. coolant temperature, flow, light-guide temperatures,
CEDAR temperature & pressure, etc..) and to generate warnings and alarms to ensure safe operation.
NA62 KTAG DCS User Requirements
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KTAG DCS Logical Structure
The KTAG DCS can be divided up into 4 sub-systems:



HV system control
NINO parameters control
CEDAR Gas Monitoring
KTAG Cooling and Environmental monitoring
HV System Control
For running with H2 there will be up to 64 PMTs per octant giving 512 in total. Assuming PMTs are individually
powered a system using 32-channel CAEN HV power supplies (eg. A1536) would need 16 such supplies requiring
one SY4527 crate.
Per channel: Set
Parameter ID
VSET
VMAX
ITRP
TTRP
VRUP
VRDN

Action
GO_TO_ON
GO_TO_OFF
Final State
ON. Voltages set to VSET
OFF. Voltages set to ZERO
Monitoring
Parameter ID
VOLTS
CURR
STATUS

Description
Operating voltage
Maximum permissible voltage
Trip current
Time at current > ITRP
Ramp up rate
Ramp down rate
Actions
The Run-control Finite State Machine (FSM) will issue commands to the DCS to change the state of the HV
systems at start-of-run and end-of-run.
Initial State
OFF
ON

Units
V
V
mA
s
V/s
V/s
Units
V
mA
logical
Description
Operating voltage
Current
ON/OFF/RAMP/ERROR
Sampling
30 s
30 s
30 s
Alarms
Condition
Severity
STATUS_MM
FATAL
VOLTS_HI
VOLTS_LO
FATAL
TRIP
FATAL
Comments
STATUS_MM is set if there is a mis-match between the requested and actual
ON/OFF state. Generally this is an indication of a communications error.
VOLTS_HI/VOLTS_LO is set if the actual VOLTS is over or under VSET by a
tolerance equal to twice the measurement accuracy.
TRIP is set if CURR exceeds the trip current, ITRP for a time period longer
than TTRP
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NA62 KTAG DCS User Requirements
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Per A1536 Card
 Monitoring
Parameter ID
TEMP

Units
Deg C
Description
Temperature of card
Sampling
30 s
Alarms
Condition
CONN_ERR
Severity
FATAL
TEMP_HI
FATAL
Comments
CONN_ERR is set if the cable is disconnected from the A1536 card.
TEMP_HI is set if the temperature of the card exceeds a programmed
maximum
Per crate: Actions
The control of HV system crates is outside the run control.
Action
ON/OFF

Monitoring
Parameter ID
STATUS
TEMP
Units
logical
Logical
Description
ON/OFF/ERROR
Sampling
30 s
HV System Naming Definition
HV channels are identified using a naming code such as:KTAG_HV_SIDE _ARRAY _PMT
Where SIDE is either JURA or SALeVe), the ARRAY defines the PMT array numbered top to bottom (00 to 03) and
PMT (00 to 63) is the number of the PMT within the ARRAY. For example;
KTAG_HV_JURA_00_34 defines the 35th PMT in the top PMT array on the JURA side.
Within each PMT array PMTs are numbered sequentially from 0 to 63 as follows;
…. Diagram to come!
HV System Hardware Summary
The HV system hardware consists of one rack containing;
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NA62 KTAG DCS User Requirements


1 HV crates
16 HV cards
Dece
SY1527
A1536
All HV system hardware will be located on the same side of the beam. The crate will be populated with 16 HV cards
arranged as follows:-
Slot
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
Side PMT Array Channel
JURA
0
00 – 31
JURA
0
32 - 64
JURA
1
00 – 31
JURA
1
32 – 64
JURA
2
00 – 31
JURA
2
32 – 64
JURA
3
00 – 31
JURA
3
32 – 64
SALV
0
00 – 31
SALV
0
32 – 64
SALV
1
00 – 31
SALV
1
32 – 64
SALV
2
00 – 31
SALV
2
32 – 64
SALV
3
00 – 31
SALV
3
32 - 64
NINO Discriminator Boards
The pulses from the PMTs are input directly into 8-channel NINO discriminator boards. For one KTAG sub-system,
up to 32 NINO chips are needed. Each NINO has 3 parameters to be set and read back via the DCS; Threshold, Bias
and Stretch. One possible implementation is that 8 NINO daughter boards will be mounted on a motherboard
which is then in turn mounted on the cooling plate associated with each PMT array. The outputs from the NINO
daughter boards pass down electrical cables to the remote TEL62 cards. Each TEL62 can take 128 NINO inputs
meaning that 4 TEL62 cards are needed in total mounted in a WEINER crate.
Per NINO board (i.e. a group of 8 channels): Set
Parameter ID Units
Description
THR
V
Threshold Voltage
BIAS
V
Bias Voltage
STR
V
Stretch

Monitoring
Parameter ID
THR
BIAS
STR
Units
V
V
V
Description
Actual threshold
Actual bias
Actual Stretch
4
Sampling
30 s
30 s
30 s
NA62 KTAG DCS User Requirements
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Per NINO motherboard: Actions
The control of NINO motherboard is outside the run control.
Action
ON/OFF

Monitoring
Parameter ID
STATUS
Units
logical
Description
ON/OFF/ERROR
Sampling
30 s
WEINER Crate: Actions
The control of the WEINER crate is outside the run control.
Action
CON/COFF
CRESET
CCOMM

Description
Turn crate ON / OFF
Reset the crate
Reset the communications
Monitoring
Parameter ID
STATUS
VOLTS
CURR
TEMP
FSPEED
Units
logical
V
A
C
rpm
Description
ON/OFF/RAMP/ERROR
Voltage
Current
Crate temperature
Fan speed in rpm
NINO Channel Naming Definition
NINO channels are identified using a naming code such as:KTAG_FE_SIDE_ARRAY_DAUGHTERCARD_CHANNEL
Where;




SIDE is
ARRAY is
DAUGHTERCARD is
CHANNEL is
JURA / SALeVe
00 to 03
00 to 07
00 to 07
For example KTAG_FE_JURA_01_05_03
5
Sampling
30 s
30 s
30 s
30 s
30 s
NA62 KTAG DCS User Requirements
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DAQ Component Naming Definitions
There will be four TEL62 boards each with 128 inputs arranged as four groups of 32. Two TEL62 groups are mapped
to one NINO mother board.
The four TEL62 boards are identified as follows:
KTAG_TEL62_SIDE_TEL62ID
Where;


SIDE is
TEL62ID is
JURA / SALeVe
00 to 01
The four TEL62 boards are mounted in a single TEL62 crate called KTAG_CRATE_TEL62.
PMT Light Pulser
It is envisaged that a light-pulsing system will be needed to flash light into the PMTs to monitor the long-term
performance of the optical system. I believe that the SPS duty cycle is a flat-top of 4.8s repeated every 16.8s giving
12s between spills in which to collect pulser data.
I am not yet sure that the control of the pulser system is a DCS issue. I would have thought that pulser data would
enter the DAQ stream in exactly the same manner as normal beam data but readout is initiated by a dedicated
trigger. Normally a SPILL gate is distributed by the SPS and this can be used to set a bit in some trigger pattern
register and to enable pulser triggers. Triggers are then formed from the output of a pulse generator in coincidence
with SPILL and the pulse generator is used to flash the LEDs.
There may be the need for some time delay between the flashing of the LEDs and the trigger pulse and perhaps the
current supplied to the LEDs (but both of these are likely to be kept fixed once set up properly).
CEDAR Gas Monitoring
It is assumed that the control for the CEDAR gas system is provided by others. However, to ensure safe operation,
the KTAG DCS system should perform the following;

Monitoring
Parameter
KTAG_CEDAR_PRESS

Signal Type
2 wire V
KTAG_CEDAR_TEMP00(_03)
4 wire T
KTAG_CEDAR_ZONE_TEMP
4 wire T
Definition
Pressure of the CEDAR gas
Temperature of the CEDAR
structure measured in 4 places
Temperature of the NA62
experimental zone just above the
CEDAR
Alarms
None – I assume all of this will be catered for by the CEDAR gas system.
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NA62 KTAG DCS User Requirements
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Whilst the KTAG DCS mainly provides a monitoring function of the CEDAR gas, periodically there will have to be
pressure scans in which physics data is taken with varying CEDAR gas pressure. Dialogue with the group providing
the CEDAR gas system will be needed to understand whether the control of the CEDAR gas pressure should be a
function of the KTAG DCS or not.
KTAG Cooling and Environment Monitoring
The heat generated in the PMTs and NINO cards is removed using a re-circulating chiller. Each KTAG sub-system has
its own cooling circuit and the two circuits are connected in parallel at the chiller. Within each KTAG sub-system the
fluid flows in series through four heatsinks to which the 32-channel NINO cards and the PMTs are connected.
Whilst the KTAG sub-systems are thermally insulated from the CEDAR, it is important that the heat flow from the
KTAG to the CEDAR is minimised. It is proposed that this will be done by manually changing the chiller set-point at
appropriate intervals.
The DCS system will need to monitor the fluid temperature, flow rate, chiller alarm status (if applicable) and the
temperatures at each PMT array location. To ensure protection in the event of H2 leakage, the KTAG enclosures will
be flushed with N2 gas. The DCS system will therefore also need to monitor the N2 flow rate into each enclosure
and the concentrations of oxygen and hydrogen. In addition to sensors dedicated to the DCS a second of H2
concentration sensors set will be used as input to the DSS to ensure safe operation.
KTAG Cooling System

Monitoring
Parameter
KTAG_COOL_STATUS

Signal Type
Volt-free contacts
KTAG_COOL_OUT_TEMP
4 wire T
KTAG_COOL_IN_TEMP
4 wire T
KTAG_COOL_JURA_FLOW
2 wire V
KTAG_COOL_SALV_FLOW
2 wire V
Definition
NC if all is OK. Contacts open in the
event of FAULT or POWER FAILURE
Temperature of the coolant
leaving the chiller
Temperature of the coolant
returning to the chiller
Fluid flow rate to JURA side subsystem
Fluid flow rate to SALeVe side subsystem
Alarms
Condition
Severity
KTAG_COOL_STATUS_ERR
FATAL
KTAG_COOL_TEMP_HI
KTAG_COOL_TEMP_LO
KTAG_COOL_JURA_FLOW_LO
KTAG_COOL_JURA_FLOW_LO
FATAL
FATAL
FATAL
FATAL
Comments
Set if the chiller control system detects a fault or the
power goes off
Set if the fluid outlet temperature is too high
Set if the fluid outlet temperature is too low
Set if the flow rate to the JURA side is too low
Set if the flow rate to the JURA side is too low
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NA62 KTAG DCS User Requirements
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KTAG Enclosure Environment Monitoring

Monitoring
Parameter

Signal
Type
Definition
KTAG_ENCL_JURA_INLET_TEMP
4 wire T
KTAG_ENCL_JURA_PMT00_TEMP
KTAG_ENCL_JURA_PMT01_TEMP
KTAG_ENCL_JURA_PMT02_TEMP
KTAG_ENCL_JURA_PMT03_TEMP
4 wire T
4 wire T
4 wire T
4 wire T
KTAG_ENCL_JURA_OUTLET_TEMP
4 wire T
KTAG_ENCL_JURA_ENV00_TEMP
KTAG_ENCL_JURA_ENV01_TEMP
4 wire T
4 wire T
KTAG_ENCL_SALV_INLET_TEMP
4 wire T
KTAG_ENCL_SALV_PMT00_TEMP
KTAG_ENCL_SALV_PMT01_TEMP
KTAG_ENCL_SALV_PMT02_TEMP
KTAG_ENCL_SALV_PMT03_TEMP
4 wire T
4 wire T
4 wire T
4 wire T
KTAG_ENCL_SALV_OUTLET_TEMP
4 wire T
KTAG_ENCL_SALV_ENV00_TEMP
KTAG_ENCL_SALV_ENV01_TEMP
KTAG_ENCL_N2_FLOW
KTAG_ENCL_H2_CONC
4 wire T
4 wire T
2 wire V
2 wire V
Temperature of inlet cooling tube
within enclosure
Temperature of PMT array 00
Temperature of PMT array 01
Temperature of PMT array 02
Temperature of PMT array 03
Temperature of outlet cooling tube
within enclosure
Gas temperature in enclosure
Gas temperature in enclosure
Temperature of inlet cooling tube
within enclosure
Temperature of PMT array 00
Temperature of PMT array 01
Temperature of PMT array 02
Temperature of PMT array 03
Temperature of outlet cooling tube
within enclosure
Gas temperature in enclosure
Gas temperature in enclosure
Inlet N2 gas flow
Enclosure H2 concentration
Sampling
30 s
30 s
30 s
30 s
30 s
30 s
30 s
30 s
30 s
30 s
30 s
30 s
30 s
30 s
30 s
30 s
30 s
30 s
Alarms
Condition
KTAG_ENCL_N2FLOW_LO
KTAG_ENCL_H2CONC_HI
Severity
FATAL
FATAL
KTAG_ENCL_JURA_TDIFF_HI
WARN
KTAG_ENCL_SALV_TDIFF_HI
WARN
Comments
Set if the N2 flow to the enclosure is too small
Set if the H2 concentration is too high
Set if the temperature difference between the average
of all 8 internal temperature sensors and the CEDAR
temperature is too high
Set if the temperature difference between the average
of all 8 internal temperature sensors and the CEDAR
temperature is too high
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