Post on 09-Aug-2020
Simulations and Analysis to optimize the design for the Mu2e ECAL
Short notice
Alessandra Lucà April 20, 2012
Outline ECAL for the Mu2e experiment
Detailed simulation LYSO crystals: shower profile Intrinsic energy resolution
Test beam @ Mami MC simulation of the prototype Data/MC comparison
Reconstruction Capabilities Clustering & Trigger algorithms
Summary
April 20, 2012 Alessandra Lucà 2
Standalone Simulation (Geant4 )
Data Analysis (Root)
Mu2e fmw Simulation (Geant4 )
April 20, 2012 Alessandra Lucà
The Mu2e experiment
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Look for 105 MeV e-
Al atoms capture µ
GOAL: Detect charged lepton flavor non-conservation in the coherent, neutrinoless conversion of a muon to an electron in the field of a nucleus with a single event sensitivity (SES) of 2 × 10−17 and to set a limit of 6 × 10−17 at 90 % C.L.
N e Nµ − −→
n p n
p
n p n
p n p n p n p
n p n p n p n p
n p n p n
μ
Coherent Conversion
Al27
e
Nuclear Recoil
Ee = mμ– Nrecoil- (B.E.)1S =104.9MeV
Alessandra Lucà 4 April 20, 2012
Beam Direction
ECAL Requirements and Capabilities
Energy Resolution < 5%
Time Resolution < ns
Spatial Resolution ≤ cm
Radiation Dose ≈ 200Gy/y
Magnetic Field 1 T
Trigger Rate 1kHz
30m
m
Single LYSO Crystal readout by APDs
12 crystals
44 c
ryst
als
Calorimeter Vane
The ECAL for Mu2e
The integral of the fitting function. Fitting function integral.
About 95% is within 3.5 RM (~ 7 cm)
Alessandra Lucà 5 April 20, 2012
Lateral and longitudinal energy profiles
Simulated calorimeter was made of 20 concentric tubes (0.5 RM thick). Length set to 28 X0
MC program has been implemented using GEANT4 to simulate the response of a LYSO crystal calorimeter to a 105 MeV electron.
Calorimeter has been divided into 56 slices along z-axis, each 0.5 X0 thick. Cylinder radius has been set to 10 RM
Average energy fraction deposited in the calorimeter,
Standalone simulation of a short Mu2e vane
April 20, 2012 Alessandra Lucà
Standalone simulation studies to evaluate all components affecting energy resolution
1) Leakage (lateral, longitudinal, albedo) 2) Photostatistics and noise Intrinsic energy resolution of about 1.5%, mainly affected by albedo.
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The prototype consists of
1) an inner matrix of 9 crystals (new LYSO SICCAS)
20x20x150 mm3 --> 10x10 mm2 APD Hamamatsu S8664-1010 2) An outer matrix, for leakage recovery, composed of 8 PbWO4 crystals of mixed dimensions: 30(40)x30(40)x130 mm3
readout by PMTs.
3) The transverse matrix coverage is 2.8 RM.
Test Beam @ MAMI: Layout of the prototype
Lyso 13 cm
Lyso 13 cm
Lyso 13 cm
PbWO
13 cm
PbWO
13 cm PbW
O 13 cm
PbWO
13 cm
PbWO
PbWO
PbWO
PbWO
PbWO 13 cm
PbWO PbWO
PbWO
PbWO
PbWO
PbWO
PbWO
PbWO
PbWO
PbWO
PbWO
Lyso 15 cm
Lyso 15 cm
Lyso 15 cm
Lyso 15 cm
Lyso 15 cm
Lyso 15 cm
Lyso 15 cm
Lyso 15 cm
Lyso 15 cm
∼2.8 Moliere radii
1 inch PMT
APD 10x10
Lyso 13 cm
PMT: 0.6 cm
Alessandra Lucà April 20, 2012 7
The test beam has been carried out at the Mainz Microtron (MAMI) facility_ Germany _ in March 2011
MC Simulation
Complete Geant-4 simulation respecting all the construction features of the matrix: dimensions, positioning, photosensors (p.e., noise), 300 μm Tyvek wrapping, beam dimensions (8 mm Ø).
Photon transportation has not been simulated, because of CPU limits.
LRU simulated a posteriori
April 20, 2012 Alessandra Lucà 8
Data/MC comparison
April 20, 2012 Alessandra Lucà 9
MeV/Ebeam
MC • Data
Erec/Ebeam
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Erec/Ebeam Erec/Ebeam
Erec/Ebeam
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Erec/Ebeam Erec/Ebeam
Erec/Ebeam
Data-MC comparison:Esum/Ebeam and σE/E
April 20, 2012
Erec/Ebeam
Entr
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Erec/Ebeam
INNER MATRIX
WHOLE MATRIX
Energy Sum in the inner and in the whole crystals matrix at 100 MeV
INNER MATRIX
WHOLE MATRIX
Alessandra Lucà 10
Mu2e framework:Event display (1)
April 20, 2012 Alessandra Lucà
Event Display for a pure single event.
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April 20, 2012 Alessandra Lucà
Event display (2) Zoom: additional energy deposits coming from background Clustering
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April 20, 2012 Alessandra Lucà
Clustering
Each cluster is reconstructed joining contiguous crystals around the cell with maximum energy deposition. From differential time distribution ∆(t), one knows that different clusters can be merged within a time window of 1 ns. In such a way, the fragments are recovered, improving energy resolution.
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April 20, 2012 Alessandra Lucà
Trigger algorithm: energy distribution on front face
90700 generated events with cosTheta(-0.5:0.5) and 20 hits in the Tracker: 61500 (70%) events on the Front Face and 27500 (30%) events on the Edges Assuming to be able to discriminate DIO from signal, on both ECAL places Effi ~ 98%
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April 20, 2012 Alessandra Lucà
Rate for 6 batches 91% efficiency @ 64 MeV DIO Rate reduction of 120: 600 kHz 4 kHz in Standalone Trigger Mode. Rejection/efficiency depends on energy resolution
Trigger: summary
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April 20, 2012 Alessandra Lucà
Simulations and Test to optimize the design for the electromagnetic calorimeter: • Standalone GEANT4 Simulation of LYSO crystals matrices ->
Detailed energy profiles for the radial and longitudinal energy deposition and leakage have been presented. The intrinsic resolution has also been shown.
• Participation @ MAMI Test Beam and Data Analysis of obtained
results with a prototype. • Detailed simulation of the prototype -> Data / MC comparison.
• Reconstruction Algorithms to test the ECAL capabilities with a full simulation of signal and bkg events in the Mu2e Framework software (among them I’ve shown simple clustering and trigger procedures)
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Summary
April 20, 2012 Alessandra Lucà 17
Backup
µ-N→e-N and µ+→e+γ
κ<<1 magnetic moment type operator µ → eγ rate ~300X µN → eN rate
κ>>1 four-fermion interaction µN → eN rate many orders of magnitude greater than µ → eγ rate
Model independent
CLFV Lagrangian:
MEGA SINDRUM II
MEG goal
Mu2e goal
∑=Λ+
+Λ+
=duq
LLLLL qqeFeRm
L,
22 )1()1(µ
µµνµ γγµ
κκσµ
κµν
April 20, 2012 Alessandra Lucà 18
New Physics scenarios for the μ --> e conversion
From W. Marciano. also see Flavour physics of leptons and dipole moments, arXiv:0801.1826
April 20, 2012 Alessandra Lucà 19
Cos’è la conversione µ →e ? La conversione coerente, senza neutrini, di un muone in elettrone a seguito di
cattura su nuclei è un esempio particolarmente interessante di un processo di LFV, nel settore carico.
Il μ- viene frenato su un bersaglio dove dà origine ad un atomo muonico, e giunge allo stato 1s
1. Cattura (≈60% Al)
2. Decadimento in Orbita (DIO) (≈40% Al)
3. Conversione coerente:
Un singolo elettrone monoenergetico. Ee = mμ – B.E. = 105. MeV (Al)
April 20, 2012 Alessandra Lucà
'N Nµµ ν− →
eN e µµ ν ν− −→
N e Nµ − −→
56( ) 10SMBR N e Nµ − − −→ ≈
Nel Modello Standard tale conversione può avvenire con un rate al di sotto dell’attuale portata di qualunque esperimento.
X e-
Coherent recoil of nucleus
µ-
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L’obiettivo di Mu2e
April 20, 2012 Alessandra Lucà
La collaborazione Mu2e ha proposto un esperimento da svolgere al Fermilab (tramite produzione di ca 1018 muoni in due anni) con l’obiettivo di osservare il processo in esame, o di ottenere un upper limit di:
Mu2E sensitivity is more than 4 orders of magnitude
beyond the current limit
Il migliore limite è stato ottenuto da SINDRUM II (‘90).
Normalizzato alla cattura: Il muone giunge all’orbitale 1s con transizioni e.m. (X-rays danno lo stop rate, tramite un rivelatore al germanio situato vicino al beam dump). Dopo la cattura Mg → Al by a 2.6 MeV β followeseguito da γ che potrebbe essere usato per il rate di cattura
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Pulsed beam
105 MeV electron delayed
Al foils: muon convert
here
Prompt!!!
Pulsed beam reduces prompt bkgs
8 GeV protons produced by the Fermilab accelerator
April 20, 2012 Alessandra Lucà 22
Backgrounds • Muon Decay In Orbit (DIO)
- High resolution in order to avoid this kind od bkg • Radiative pion capture • Radiative muon capture
April 20, 2012 Alessandra Lucà
Back
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Alessandra Lucà April 20, 2012
Prompt Background and Choice of Z
chosen Z based on tradeoff between rate and lifetime: longer lived reduces prompt backgrounds
Back
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Alessandra Lucà April 20, 2012
Transverse-tracker
Beam Z
18 “stations” spanning ~3 m length
• 18 stations • Each station has 2 planes … 36 planes • Each plane has 6 panels … 216 panels • Each panel has 2 layers … 412 layers • Each layer has 50 straws …
21,600 straws • Two readout channels per straw …
43,200 readout channels
6 Panels 60° rotation
The tracker momentum resolution for 100 MeV electrons is about 300 keV and is
dominated by multiple scattering in the tracker.
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Light Yield del NaI ∼ 40000 γ/MeV
Crystals for HEP (High Energy Physics)
April 20, 2012 Alessandra Lucà 26
CR test (Inner Matrix) - Calibration CR test for the equalization of response carried out (T~ 24 C) by triggering with an external scintillation counter on top of the prototype. clean-up the events by selecting “clean” fired columns for the inner matrix. Calibration of the single channel at a level of 2% M(APD) ~ 120 Average MIP ~ 100-120 counts
No energy in the lateral columns
Alessandra Lucà April 20, 2012
Back
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Noise test of the matrix
We summed the charge of the 9 LYSO+ APD crystals. Same thing done for the 8 PBWO+PM of the external matrix (1) Overall NOISE LYSO ~ 3.2 Counts. (2) Assuming MIP~ 100 Counts
σ(noise) = 3.2*20 MeV/100 = 620 keV
Excellent scaling with √(Nch) ~200 KeV single channel noise
Overall PBWO+PM noise ~ 2 counts We have a total 3.6 counts, 720 keV of noise.
Alessandra Lucà April 20, 2012
Back
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Linearity
Total energy deposit and beam energy Ratio
Inner matrix
Whole matrix
April 20, 2012 Alessandra Lucà 29
Position Reconstruction
Position Scan aloong X Δx=5mm, X0=-1.7mm
Energy Resolution along X
April 20, 2012
Orizontal Scan : energy reconstruction
Alessandra Lucà 30 30
Disuniformity contribution to energy resolution
Back
Source of calibration
19F + n → 16N + α 16N → 16O* + e− + νe 16O* → 16O + γ (Eγ = 6.13 MeV)
Activated Fluorinert is pumped through tubes into crystals (ECAL front face).
Source : FluorinertTM FC-77 (C8F18) Decay process:
t1/2 =7 s
Neutron produced by a DT generator. d + t → n(14.2 MeV) + α Rate =109 n/s
April 20, 2012 Alessandra Lucà 32
A typical energy spectrum measured in a calorimeter can be approximated by the Logarithmic Gaussian function [Di Claus Groupen, Schwartz, “Particles Detectors”, Cambridge University Press (2008)]
Logarithmic Gaussian function
April 20, 2012 Alessandra Lucà 33
Particle ID
Muons not stopping in target can have momenta up to 100 MeV (~ 10-4)
Muons deflecting up to 30/40 degrees could mimic a conversion electron
Fortunately they are “prompt” m.s. in 17 targets below 10 degrees Probability of large deflections by elastic
scattering?? P ~ 10^{-3}
1) mu- response on the EMC with Geant4 2) Activated Atomic and Nuclear Captures 3) X-checked endpoint and DIO fraction on Al, gold, Pb 4) X-checked calculation of EndPoints 100 k events with mu- impinging on a Standalone matrix of LYSO crystals
Back
April 20, 2012 Alessandra Lucà 34
Test beam @ Mami
Dopo un primo test effettuato nel 2009 @ BTF( Beam Test Facility dei LNF) con un prototipo più piccolo, abbiamo costruito una matrice prototipo di dimensioni più grandi per testarla con un fascio di fotoni @ MAMI (Marzo 2011).
April 20, 2012 Alessandra Lucà
Nella sala A2 il fascio di elettroni viene convertito in un intenso (~108 γ sec-1) fascio di fotoni reali attraverso bremsstrahlung in un sottile radiatore (foglio metallico). Il momento degli elettroni scatterati in questo processo viene analizzato da uno spettrometro costituito da uno scintillatore plastico che fornisce una misura dell’energia del fotone associato per bremsstrahlung con una risoluzione di pochi per mille. Fascio di fotoni taggati con
eccellente ∆P(FWHM) = 1 MeV Rate selezionabile (da pochi kHz fino
al MHz) & energia nell’intervallo 20-380 MeV
Spot del fascio di fotoni sul calorimetro di ~ 8 mm di diametro
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Assemblaggio della matrice: cablaggio dell’elettronica
Alessandra Lucà April 20, 2012 38
Assemblaggio della matrice: ermeticità & cablaggio
Alessandra Lucà April 20, 2012 39
ADC Count
Entr
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Scan in Energia
QTOT =Qi − Pi
Mi
M
i∑
• Dopo aver calibrato i canali con le particelle al minimo (MIP) ed aver effettuato i run di piedistallo sono state selezioante 11 energie tra 40 e 300 MeV.
April 20, 2012 Alessandra Lucà 40
MeV/Ebeam
MC • Data
Data/MC comparison
April 20, 2012 Alessandra Lucà Erec/Ebeam
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Erec/Ebeam
▪ MC ● Data
Data/MC comparison (external matrix)
April 20, 2012 Alessandra Lucà
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Erec/Ebeam Erec/Ebeam
Erec/Ebeam
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April 20, 2012 Alessandra Lucà
Trigger & Cluster
Un algoritmo (filtro ) di Trigger è necessario per: (i) ridurre la scrittura su disco di una grande quantità (100-300) in modo da portare i 300 PB/year a O(PB) storage (ii) oppure ridurre il il flusso di Dati dal rivelatore da 30 GB/s pochi 100 MB/s Il FILTRO dovrebbe essere efficiente O(90%) per eventi di segnale.
L’ EMC puo’ svolgere tale ruolo. Il punto (1) puo’ essere ottenuto anche a livello di FPGA del DAQ per avere maggiore flessibilità. 100 k eventi (Signale+DIO) simulati nel Framework + un semplice algoritmo di clustering usato per unire celle contigue. - cluster divisi in due zone: Front Face or Edges. - raggio interno dell’ EMC @ 390 mm. - studio in funzione della risoluzione energetica dell’EMC.
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Event display (2)
April 20, 2012 Alessandra Lucà
Event Display per un evento tipo: segnale + fondo I fondi prodotti dalla cattura creano segnali spuri sul tracciatore che possono inficiare la ricostruzione della traccia
Blue text: beam related. 44