Multi-Anode Photomultiplier (MAPMT) Readout for High ...€¦ · The hadronic sampling calorimeter...
Transcript of Multi-Anode Photomultiplier (MAPMT) Readout for High ...€¦ · The hadronic sampling calorimeter...
Choice of Photomultiplier
Possible performance improvements
Optical Coupling Choices
Motivation
Optics
Cesium Scan
Proposed Concepts Readout Schematics in Development
Tile Long Barrel (LB)(|η| < 1.0)
Tile Extended Barrels (EB)(0.8 < |η| < 1.7)
Multi-Anode Photomultiplier (MAPMT) Readout for High Granularity Calorimeters
Tigran Mkrtchyan, ANSL, Yerevanon behalf of the ATLAS Tile Hadron Calorimeter Group
The conducted preliminary studies focus on the feasibility of increasing the readout granularity specifically of the ATLAS Tile hadronic calorimeter
The hadronic sampling calorimeter is made of steel absorbers, scintillating tiles with wavelength shifting fibers64 wedge-shaped modules with Δϕ = 0.13 radial layers: A (Δη=0.1), BC(Δη=0.1), D(Δη=0.2)
The use of multi-anode photomultipliers (MAPMT) creates a possibility to increase the spatial resolution of the calorimeter:● A layer by a factor of 4 Δη=0.1 0.025● BC layer by a factor of 2 Δη=0.1 0.05
Expected improvements of TileCal:● Reconstruction of physics objects: missing Et, tau and jets● Angular position of jets and single hadrons● Reconstruction of jet properties (shapes, masses)● Jet position● 3D topological clusters● precise life-time measurements of long lived particles
1. Lens system:● Telescope in the volume
between the WLS fiber bundle and MAPMT● Variable magnification factor:x3 for A-Cells, x2 for B,C-
cells● Large beam divergence additional focusing lens
2. Optical guide:● Made of WLS or clear fibers with the same numerical aperture as in the original bundle● Exact arrangement of fibers fed through to a grid pattern fitting to the anode geometry
● No change of the PMT block selection of a multi-channel sensor with same geometry and dimensions as the current Hamamatsu R7877● Hamamatsu R7600-300-M64 with 64 anodes, sensitive surface area of 18mm x 18mm● The light from each excited tile is collected by WLS fibers, which form a bundle for each cell
Front-end input stage performing analog sum of the output
Front-end board with digital sums
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Signal crosstalk:● Spatially well separated two fibers excited with an LEDin an isolated testing environment● With non-optimized arrangement, the measured crosstalk in neighboring pixels is typically less than 10%
3. Air gap:● Fibers in a mock-up bundle were individually excited with an LED●The MAPMT response to a single fiber light emission as a function of the fiber bundle-cathode distance shows an almost constant amplitude up to 5mm
● Typical anode charge from non split cell readout with single-anode PMTs is ~7 Me- per GeV (PMT gain set to 105)The expected charge for MAPMTs with the same conditions is ~0.1Me-
per GeV
● Fast signal processing will require about a factor of 3 increase in average for the required bandwidth w.r.t. the full single anode readout scheme
● Partial sums of all signals in each sub-cell will carry the energy-deposit information and be processed in real-time at 40MHz
High granularity readout electronics must comply with the following constraints:● minimum modification of any element of the baseline architecture● minimum impact on the Low and High Voltage distribution systems● not require modification of the mechanical structure of the drawers● send up to 5 configurable sums (1 global and 4 partial) of the signals from the MAPMT and process them with current electronics chain for single-anode PMTs
A 137Cs -source is moved with constant (20cm/s) speed through each individual tile through a pipe filled with liquid.● Readout electronics acquire integrated currents from one channel connected to the single-anode PMT and 46 channels to the central part of the MAPMT● Both single and multi-anode PMTs are connected to the same calorimeter cell from different sides
● Comparison of time-dependent response curves of the single-anode and individual anodes of the MAPMT allows to correlate them to individual tiles● Measurement of the readout cross-talk allows to compute weights for each pixel response to be used in the partial sums for forming a sub-cell response
Cell A12 time profile:● 9 scintillating tiles per rowIndividual MAPMT channels with maximum amplitude at given local single-anode maximums
Cell B11 time profile:● 16 scintillating tiles per row ● Cross-talk larger w.r.t. cell A12,same pixel has a maximum response for two different positions of the source
Mock-up fiber bundle exit face as in the detector
From left to right:R7600-300-M64, R11187(spares)R7877(used in Tile)
Current TileCal cell size becomes comparable with typical separation between 2 quarks from W decay at high pT (> 600 GeV)
Higgs, W, Z, top decay to narrow jets with radius smaller than 0.4 in η x ϕ,which contain 2 or 3 sub-jets
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● Dividing the the BC layer into B and C will provide more information on the longitudinal shower profile● Splitting the A layer along η should help gain more information on the shower transverse profile
Readout Electronics
The PMT block:● Present(upper) block ischanged by replacing the PMT with a same sized multi-anode sensor● The PMMA light guide is removed and a suitable optical coupler is inserted to map the fiber bundleonto the MAPMT photocathode
● Analog sums of 8 + 8 channels● Programmable analog gainand number of summation channels● USB or Serial interface with host PC
NDIP17 3 - 7 July 2017, Tours, France
● PCB design with analog components
● Daughterboard design with CPU for handling controls and interfaces
mZ' = 1.6 TeV