Temperature Sensors on Endcap MDT chambers.
Edward Diehl Jan. 19, 2006

I.  Types of Sensors

There are 3 different types of temperature sensors used on MDT endcap chambers:
  1. Washington (UW) temperature sensors, 20 of which are mounted on all EML, EMS (except EMS1), and EIL4 chambers.  These are mounted on the end and side cross-beams of the chamber spacer frame and are read out via the DCS box on the readout end of the chamber.
  2. Brandeis RTD temperature sensors, 8 of which are mounted on corners of the end crossbeams of EIS, EIL (except EIL4), and EMS1 chambers.  EML1 also has 8 RTD sensors, but mounted in different locations than the other chambers (it also has 20 UW sensors).  RTD sensors are read out by the LWDAQ multiplexer (AMB) on the HV end of the chamber.
  3. Nikhef temperature sensors, which are also used on the barrel MDT chambers are used on EO chambers.  These are read out via the DCS box on the readout end of the chamber.
The reason for 3 different sensors types is historical.  Originally Nikhef was to supply all temperature sensors.  Washington felt that they could install more and better sensors for a similar price so they designed their system, which was originally supposed to be used on all EI and EM chambers.  Later there was some concern that the "offsets" of the UW sensors could be affected by exposure to radiation which could be an issue for the chambers close to the IP.  Hence, BMC opted to use less-radiation sensitive platinum resistance temperature sensors ("RTD" sensors) on the EIS1, EIS2, EIL1, EIL2 and EMS1.

II.  Locations of Temperature sensors.

The locations of the temperature sensors are described by a location number [1-20] as shown in Figure 1 and defined in Table 1.  Table 1 also lists a text descriptor that can be used instead of the location number.  All chambers use the first 8 locations.  The rest are only used by chambers with UW sensors.  Notice that odd-numbered locations are on ML1, and even are on ML2.  The locations are schematic: for exact locations of sensors one must refer to chamber mechanical drawings.

Figure 1.  Temperature sensor locations.  Chamber coordinate system is shown.

Temperature sensor locations


Table 1.  Temperature sensor locations and descriptors
Location  Num Descriptor



RO crossplate ML1 short side 1 T<type>_<chamber>_ML1_RO_S
RO crossplate ML2 short side 2 T<type>_<chamber>_ML2_RO_S
RO crossplate ML1 long side 3 T<type>_<chamber>_ML1_RO_L
RO crossplate ML2 long side 4 T<type>_<chamber>_ML2_RO_L
HV crossplate ML1 short side 5 T<type>_<chamber>_ML1_HV_S
HV crossplate ML2 short side 6 T<type>_<chamber>_ML2_HV_S
HV crossplate ML1 long side 7 T<type>_<chamber>_ML1_HV_L
HV crossplate ML2 long side 8 T<type>_<chamber>_ML2_HV_L
Short longbeam ML1 near HV side 9 T<type>_<chamber>_ML1_SB_H
Short longbeam ML2 near HV side 10 T<type>_<chamber>_ML2_SB_H
Center crossplate ML1 short side 11 T<type>_<chamber>_ML1_SB_C
Center crossplate ML2 short side 12 T<type>_<chamber>_ML2_SB_C
Short longbeam ML1 near RO side 13 T<type>_<chamber>_ML1_SB_R
Short longbeam ML2 near RO side 14 T<type>_<chamber>_ML2_SB_R
Long longbeam ML1 near HV side 15 T<type>_<chamber>_ML1_LB_H
Long longbeam ML2 near HV side 16 T<type>_<chamber>_ML2_LB_H
Center crossplate ML1 long side 17 T<type>_<chamber>_ML1_LB_C
Center crossplate ML2 long side 18 T<type>_<chamber>_ML2_LB_C
Long longbeam ML1 near RO side 19 T<type>_<chamber>_ML1_LB_R
Long longbeam ML2 near RO side 20 T<type>_<chamber>_ML2_LB_R

The general descriptor:

        T<type>_<chamber>_ML<N>_<side>_<side_location>  where

<type> = "B" for Brandeis RTD temperature sensor

= "W" for Washington temperature sensor

= "N" for Nikhef temperature sensor
<chamber> = chamber name, e.g. eml4c01
<N> = Multilayer number [1:2]

= "HV" for HV side crossbeam

= "SB" for short side longbeam

= "LB" for long side longbeam
<side_location> = location of sensor along a given side.

= "S" for towards the short longbeam side

= "L" for towards the long longbeam side

= "H" for towards the HV side

= "R" for towards the readout side

= "S" for towards the short longbeam side

= "C" for at the center of a longbeam (really on the center crossbeam)


Example:  TW_EML1C15_ML1_RO_S  => This is a Washington T sensors mounted on ML1 of EML1C15 at the readout end near the short side of the chamber.

Notice that the locations have been defined in terms of the readout (RO) and high voltage (HV) ends of the chamber, rather than in terms of the ATLAS chamber coordinates.  The reason for this is that we expect the temperature of the RO and HV ends to be different due to the large power comsumption of the readout electronics, and so temperature should track RO/HV end rather than ATLAS X coordinate.   With this scheme it one would expect symmetry between the identically numbered sensors on the "A" and "C" sides of ATLAS.

The correspondence between chamber location and readout channel is given in Table 2.  The table shows the nominal values of channel to location correspondence.  If T sensor cables are installed at the wrong locations and/or mis-wires, there will be exceptions to this mapping.  The DB files record any known misplacement of T sensors.

Table 2. Channel - location number coorespondence for all T sensors types.  (Except EO/Nikhef sensors for the time being).   A blank indicates that no sensor exists with that channel number.  This table is slightly confusing since the different types of temperature sensors are read out with different electronics.

RTD sensors UW T sensors
Channel EIS1, EIS2, EIL1, EIL2, EMS1  EML1 EML, EMS (except EMS1) EIL4

"L" "S"
"L" "S"







0


1 2 20
1 1  2 5 2 1 19
2 5  6 6 13 14 18
3 6  5 9 14 13 17
4 2  1
 10 3 4 16
5 3  4
 11 4 3 15
6 7  8 12 19 20 8
7 8  7
 13 20 19 7
8 4  3
 14 11 12 6
9


12 11 5
10


9 10 10
11


10 9 9
12


17 18 12
13


18 17 11
14


15 16 14
15


16 15 13
16


5 6 2
17


6 5 1
18


7 8 4
19


8 7 3

III. Washington Temperature Sensors.

Twenty of these sensors are installed on all EML and EMS chambers (except EMS1), and EIL4. Table 3. gives the correspondence between the readout channel and the physical location of the sensor (using location numbers as defined above - remember that odd numbers are on ML1 and even on ML2).   Also listed in the "string" information which relates to the physical cabling of the sensors and is explained in a separate document.

These sensors have 2 calibration constants: an offset and a slope. All these constants have been measured at Washington.  Washington installed both "UW" and "RTD" sensors on EML1 in order to cross-check the "UW" sensors.  Note that in most endcap locations the expected radiation levels are not expected to affect the "UW" sensors, so these drifts are not expected to be a problem.

Table 3.  Washington Temperature Sensors channel - location correspondence.
 String Channel Location "L" chamber Location "S" chamber EIL4
 Description






String1-1 short 0 1 2 20
 RO crossplate short side
String1-1 long 1 2 1 19
 RO crossplate short side
String1-2 short 2 13 14 18
 Short longbeam near RO side
String1-2 long 3 14 13 17
 Short longbeam near RO side
String2-1 short 4 3 4 16
 RO crossplate long side
String2-1 long 5 4 3 15
 RO crossplate long side
String2-2 short 6 19 20 8
 Long longbeam near RO side
String2-2 long 7 20 19 7
 Long longbeam near RO side
String3-1 short 8 11 12 6
 Center crossplate short side
String3-1 long 9 12 11 5
 Center crossplate short side
String3-2 short 10 9 10 10
 Short longbeam near HV side
String3-2 long 11 10 9 9
 Short longbeam near HV side
String4-1 short 12 17 18 12
 Center crossplate long side
String4-1 long 13 18 17 11
 Center crossplate long side
String4-2 short 14 15 16 14
 Long longbeam near HV side
String4-2 long 15 16 15 13
 Long longbeam near HV side
String5-1 short 16 5 6 2
 HV crossplate short side
String5-1 long 17 6 5 1
 HV crossplate short side
String5-2 short 18 7 8 4
  HV crossplate long side
String5-2 long 19 8 7 3
  HV crossplate long side


IV. Brandeis Temperature sensors

These sensors are platinum 1kohm resistance-temperature devices (RTD). This is one of the Brandeis LWDAQ devices read out by A2053 RTD Head device which can read out up to 11 RTD temperature sensors. These sensors work by measuring the voltage drop across a platinum resistor fed by a constant-current source.  These sensors have one calibration constant, an offset, which is dependent on the specific cabling of each sensor.

The following MDT chambers are equipped with 8 of these sensors (all others none):
In both cases the sensors are plugged into connectors 1 and 2 on the A2053 board and hence use RTD channels 1-8.   Table 4. gives the correspondence between the readout channel and the physical location of the sensor for EIS1, EIS2, EIL1, EIL2, EMS1 and Table 5. gives the locations on EML1.

Table 4. Location of RTD T sensors on EIS1, EIS2, EIL1, EIL2, EMS1.
Channel Location "L" chamber Location "S" chamber Description
1 1 (ML1)
 2 (ML2)
 RO crossplate short side
2 5 (ML1)
 6 (ML2)
 HV crossplate short side
3 6 (ML2)
 5 (ML1)
 HV crossplate short side
4 2 (ML2)
 1 (ML1)
 RO crossplate short side
5 3 (ML1)
 4 (ML2)
 RO crossplate long side
6 7 (ML1)
 8 (ML2)
 HV crossplate long side
7 8 (ML2)
 7 (ML1)
 HV crossplate long side
8 4 (ML2)
 3 (ML1)
 RO crossplate long side

Table 5. Locations of RTD T sensors on EML1.  These sensors at locations closest to the beam where radiation exposure is highest.  The purpose of these sensors is to allow comparison with the UW T sensors also mounted on these chambers to check whether the UW sensors are affected by radiation.
Channel Location  Description
1 5 (ML1)
 HV crossplate short side
2 6 (ML2)
 HV crossplate short side
3 9 (ML1)
 Short longbeam ML1 near HV side
4 10 (ML2)
 Short longbeam ML2 near HV side
5 11 (ML1)
 Center crossplate ML1 short side
6 12 (ML2)
 Center crossplate ML2 short side
7 13 (ML1)
 Short longbeam ML1 near RO side
8 14 (ML2)
 Short longbeam ML2 near RO side



V. Nikhef Temperature Sensors on EO chambers.

Each EO chamber has 8 thermosensors (NTC type) developed by Nikhef. They are located on internal layers (wrt. the spacer) of each ML, near the corners at distance 100 mm from corresponding wire locator (i.e. from the end of the chamber). These sensors are read out by channels 0-7 of the DCS.  The sensors are attached to aluminium cylindrical shape pieces glued between tubes 2-3 and 46-47 (6-step chambers) or 54-55 (7-step chambers) as shown in fig.2. In local coordinate system Y coordinate of the sensors 0,1,2,3 is -82mm (ML1) and +82 mm for sensors 4,5,6,7 (ML2).  Table 6 gives the temperature sensor locations on EO chambers.

Table 6. Locations of Nikhef T sensors on EO chambers.
Channel EOL Location
 EOS Location
 Description
0
 7  (ML1)
 8 (ML2)
 HV crossplate long side
1 3  (ML1)
 4 (ML2)
 RO crossplate long side
2 1  (ML1)
 2 (ML2)
 RO crossplate short side
3 5  (ML1)
 6 (ML2)
 HV crossplate short side
4 8  (ML2)
 7 (ML1)
 HV crossplate long side
5 4  (ML2)
 3 (ML1)
 RO crossplate long side
6 2  (ML2)
 1 (ML1)
 RO crossplate short side
7 6  (ML2)
 5 (ML1)
 HV crossplate short side



EO Temperature Sensor
Temperature sensor on EO chamber