ProtoDUNE SP – Slow control temperature gradient monitor Giovanna Lehmann – Xavier Pons CERN 11/05/2017

IFIC and Hawai CERN/DT temperature readout test setup results. NI-9238 Data ±500 mV Range, 24 bits resolution 4 simultaneous differential channels, 250Vrms isolation Error ±0.07% MAX ~ ±30 mK MAX, Valencia setup ±7.5 mK (Measured in a fixed 25Ω resistor) Input Impedance > 1GΩ Current source Based on Texas Instruments Precise voltage reference application http://www.ti.com/lit/an/sboa046/sboa046.pdf Hawai calibration: 1000µA ±1µA ~ Max. Error ± 42 mK Results: https://indico.cern.ch/event/625009/ Valencia Calibration: 1000µA ±0.1µA ~ Max. Error ± 4 mK

Proposal 1- Temperature Gradient Monitor Readout Hardware - Input PCB. According the specifications. The gradient monitors will be connected in the flange by means of DB25 pin connector So , 6 PT100 (4 wires) x connector Proposal To use a PCB for 6U crate size with 4 DB25 connectors Capacity 24 PT100 per PCB 6U crate size PCB with 4 DB25 connectors. CERN EP/DT

Proposal 2. Temperature Gradient Monitor Readout Hardware – Multiplexer. To multiplex the 24 PT100 signals to the same Analogue Input of the NI 9238 module Multiplexer from Analog Devices Type ADG707 Datasheet 8 differential signals per multiplexer 3 multiplexers needed for 24 channels connected in cascade Control bits from NI device

Proposal 3. Temperature Gradient Monitor Readout Hardware – Current source One single current source per 6U PCB, so for 24 PT100 Current source in serial for all PT100 The serialization is done at PCB level Advantages Removes the offsets generated by individual current source calibration Easy calibration Simple design Cheaper Disadvantages If one PT100 breaks we lose all chain. This can be fixed by little bridge inside the PCB in the terminals/pad of the damaged PT100

Proposal 4. Temperature Gradient Monitor Readout Hardware – Amplifying the working temperature range With the present configuration we are wasting resolution and unused temperature range The NI 9238 is measuring from 0-250 mV that with 1 mA would represent that we measure from 33K to 673 K The solution is to adapt/amplify the signal between a working or nominal threshold to the measuring range and resolution of the NI module. With the proposed voltage divider circuit the R2 defines the working range which is amplified. Proposed Instrumentation amplifier the Texas Instruments INA116 Datasheet Amplification factor 1 to 1000

Proposal 4. Temperature Gradient Monitor Readout Hardware – Amplifying the working temperature range The following R values provides a working range of the PT100 between 15 Ω and 75 Ω Corresponds to 65 K to 210 K If we apply amplification factor = 4 then the 60mV range is amplified to 0 - 240mV range that fits with the measurement range of the NI module. If we chose narrow working range will have better resolution and accuracy. Is this useful?

DB25 FLANGE CONNECTOR MAPPING – COMPATIBLE WITH FLAT RIBBON TWISTED CABLE

DB25 CERN CABLE SPECIFICATIONS

Backup

Effect of the wire resistance of a PT100 in 4-wires connection in the SP Gradient monitor Analogue Input Impedance > 1GΩ Valencia wires 34.63 Ω/ 100 m; 20 m; 6.926 Ω x 2; 13.852 Ω Cern cable; 85 Ω/km; 20 m; 1.7 Ω x 2; 3.4 Ω Total Resistance; 17.252 Ω Worst case room temperature 298 K; PT100 voltage for 1mA current ~ 110 mV; Current at the input = 0.11 nA Voltage drop due to 17.252 Ω wire resistance ~ 1.9 nV (negligible?)