MAGNETIC MEASUREMENTS in PH-DT-DI
F.Bergsma 25-6-2010
Activities:
 Calibration of magnetic sensors in three dimensions, conversion programs
 Construction of magnetic sensors, read-out systems
 Construction of measurement benches, pneumatic motors, control programs
 Calculation of magnetic fields using FEM programs
 Service area: test magnets
 Loan equipment: Gauss meters, flip coils, integrators
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3D calibration = parameterization of the Hall voltage at many θ and
φ values , not only at θ = 0
Necessary if a precision better than 1 % is needed
ideal
For example
cross sensitivity
l,n,m= x or y or z
Planar Hall Effect :
“3D Hall Effect” :
Reasons: magneto-resistance, geometrical, material type ….
The orientation of the Hall probe should be very precisely known => rotate !
2
Head of 3D calibrator
3
3D calibrator max 1.5 Tesla
propeller
Peltier
NMR
motors
B
interface
driving axes
thermal isolation
Air flow on external
radiator of Peltier
head
4
New set-up max 2.5 Tesla
5
3D-magnetic sensor and read-out
Joint project NIKHEF-Amsterdam/CERN
•
B-sensor calibrated in three dimensions
B-SENSOR
•
Passive backplane for flat cable connector
BATSPI
•
Active backplane with CAN-interface
BATCAN
•
Relay-card with place for 4 SPI daisy-chains
controlled by CAN, interrupt lines
(tested with four chains of 32 cards)
mBATCAN
All components are producible by CERN
6
Single-row 10 pin
connector
thermistor
Homogeneous field region is small => need high
density => single row connector
Glass cube with 3 Hall probes
B-sensor card
Stack of B-sensors in calibrator
Double row flatcable connector
SPI-interface
front
back
Passive backplane for B-sensor
to carry double-row connector
Daisy chain B-sensors
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BATCAN: active backplane
with CAN interface
CAN-bus
Micro controller
front
back
Relay-card with place for 4 SPI daisy-chains
controlled by CAN
SPI-bus
CAN-bus
Passive backplane
mBATCAN
Place for 4 chains
B-sensor
8
Mixed system
32 cards/chain possible
= B-sensor
= BATCAN
= mBATCAN
SPI
SPI
SPI
CAN
CAN
4 chains/mBATCAN possible
128 cards/CAN node
mBATCAN for many B-sensors
at short distance (SPI)
BATCAN for single B-sensors at
long distance (CAN)
Software automatically finds all connected CAN-nodes and B-sensors,
the user should only care about the position of each ID
9
Users of 3D B-sensor + read-out
At CERN
ATLAS toroids monitoring system with about 1800 sensors 1.4 Tesla
mapping of solenoid 48 sensors 2.5 Tesla
CMS
field monitoring 100 sensors 1.4 Tesla
solenoid mapping 10 sensors 4.5 Tesla
LHCb mapping dipole 60 sensors 1.0 Tesla
ALICE mapping dipole 60 sensors 1.0 Tesla
mapping L3 solenoid 40 sensors 0.6 Tesla
Outside CERN:
EUDET
AMS
T2k
MICE
TPC test solenoid 24 sensors 1.0T
15 sensors 1.0 Tesla
mapping 89 sensors 0.2 Tesla, monitoring 8 sensors 0.2 T
24 sensors 4.5 Tesla calibrated, mapping to be done
Future clients : CMS, NA62, AEGIS, MICE
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BENCHES
11
ATLAS 2006
12
ATLAS pneumatic bench
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LHCb
60 addressable
B-sensors
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ALICE
15
basket
89 B-sensors
T2k: mapper
inside UA1
magnet
rails
16
Pneumatics controlled by
Piezo valves
89 B-sensors on SPI-bus
Y-movement
Pneumatic motor Z
Pneumatic motor Y
Pneumatic motor Z
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T2k pneumatic moteur Z
courroie
Boite a vitesse
Piezo g/d
moteur
huilheur
Piezo pression
Vis sans fin
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AMS permanent magnet May 2010
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Magnetic test facilities
Building 168
Power supply MNP24/Pt7
MNP24
Power supply MNP17
MNP17
Current
switch
Pneumatic
testbench
PT7
Test 3D bench
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Summary of services :
1 High precision B-sensors, calibrated in three dimensions
2 Read-out system for B-sensors
3 Benches for magnetic field mapping
4 Pneumatic motors for movement inside strong magnetic fields
5 Calculation of magnetic field
6 Assistance : Test area, loan of equipment
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STAR
BNL 1998
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HARP 2000
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