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Lucia Bortko | Design studies for BeamCal using new beam parameters | 2013-05-28 | Page 1/13
Design Studies for BeamCal
using new Beam Parameters
Lucia Bortko, DESY – Zeuthen
ECFA Linear Collider Workshop | DESY - Hamburg | 27-31 Mai 2013
Lucia Bortko | Design studies for BeamCal using new beam parameters | 2013-05-28 | Page 2/13
Goal and Motivation
Increase efficiency of reconstruction on top of the background (BG)
for showers produced by single high energy electrons (sHEe) in
BeamCal
The way to go: increase signal-to-noise ratio (SNR) in pads
Change of design: new segmentation keeping the number of
channels
Lucia Bortko | Design studies for BeamCal using new beam parameters | 2013-05-28 | Page 3/13
Beam Calorimeter for ILC
• Tungsten absorber
• Diamond sensor
• Readout plane/air gap 1 𝑿𝟎
BeamCal aimed:
- Detect sHEe
- Determine Beam Parameters
- Masking backscattered low
energetic particles
Beam parameters from the ILC
Technical Design Report
(November 2012)
- Nominal parameter set
- Center-of-mass energy 1 TeV
Lucia Bortko | Design studies for BeamCal using new beam parameters | 2013-05-28 | Page 4/13
BeamCal Segmentation
Uniform
Segmentation (US)
pad sizes are the same
Proportional
Segmentation (PS)
pads sizes are proportional to the radius
Similar number of channels
Y, c
m
Lucia Bortko | Design studies for BeamCal using new beam parameters | 2013-05-28 | Page 5/13
Energy Deposition due to Beamstrahlung
US
RMS
PS
Beamstrahlung (BS)
pairs generated with
Guinea Pig
Energy deposition in
sensors from BS
simulated with
Geant4
→ considered as
Background (BG)
RMS of the averaged
BG
→ considered as
noise (for SNR)
𝑬𝒅𝒆𝒑 is the same, but 𝑬𝒅𝒆𝒑/pad is different!
Average
10 BX
Figures show sum of all layers
Average
10 BX
Lucia Bortko | Design studies for BeamCal using new beam parameters | 2013-05-28 | Page 6/13
Single High Energy Electrons
- sHEe of different energies (10, 20, 50, 100 GeV)
are sent to each sensor ring
- Showers are simulated with Geant4
- Energy deposited in shower core
→ considered as signal
Signal-to-noise ratio:
SNR = signal from HE electronRMS from background
Example of shower from 100-GeV electron with core in ring
at R = 8 cm
Lucia Bortko | Design studies for BeamCal using new beam parameters | 2013-05-28 | Page 7/13
Evaluation around the Shower Maximum
Maximum in
10th layer In 9th layer
In 7th layer In 8th layer
Longitudinal shower profile (average over 10 showers):
100 GeV sHEe 50 GeV sHEe
10 GeV sHEe 20 GeV sHEe
Lucia Bortko | Design studies for BeamCal using new beam parameters | 2013-05-28 | Page 8/13
Proportional
Segmentation
Uniform
Segmentation
Core signal in layer of shower maximum (10th layer for 100 GeV)
RMS from Background (in 10th layer)
Uniform
Segmentation
Signal and RMS for both Segmentations
20 bunch crossings were given
Signal nearly
segmentation-
independent!
Different
distributions! Proportional
Segmentation
Lucia Bortko | Design studies for BeamCal using new beam parameters | 2013-05-28 | Page 9/13
Layer 8
Shower maximum – Layer 10
Layer 12
PS
US
PS
US
PS
US
SNR for 100 GeV Electron
Lucia Bortko | Design studies for BeamCal using new beam parameters | 2013-05-28 | Page 10/13
Efficiency for 200 GeV Electron
PS
US
sHEe 200 GeV
Lucia Bortko | Design studies for BeamCal using new beam parameters | 2013-05-28 | Page 11/13
Charge range estimate
Diamond PS
US
PS US
For Diamond sensor pad thickness 300 µm:
- Charge collected from MIP: 2.44 fC
- Maximum charge collected – for shower from 500 GeV electron: 12214 fC
(correspond to about 5000 MIPs)
Distribution of the collected charge per pad from
Background for Diamond
Distribution of the collected charge per pad from
500Gev electron showers for Diamond
Showers Background
Lucia Bortko | Design studies for BeamCal using new beam parameters | 2013-05-28 | Page 12/13
Conclusions
> New beam parameters has been released in ILC TDR (November 2012)
> Performance of Beamcal for two different sensor segmentations was compared
Number of readout channels is kept similar
Signal from sHEe nearly independent of the segmentation
Energy deposition per pad from beamstrahlung differs significantly
Proportional segmentation improves the signal-to-noise ratio
Proportional segmentation gives better reconstruction efficiency
> The charge range has been estimated
Collected charge per pad from sHEe nearly independent of the segmentation
Collected charge per pad from BS for US in 6 times more than for PS
Lucia Bortko | Design studies for BeamCal using new beam parameters | 2013-05-28 | Page 13/13
Thank you for your attention!
Lucia Bortko | Design studies for BeamCal using new beam parameters | 2013-05-28 | Page 14/13
Layer 7 Layer 11
Shower maximum – Layer 9
PS
US
PS
US
PS
US
SNR for 50 GeV Electron
Lucia Bortko | Design studies for BeamCal using new beam parameters | 2013-05-28 | Page 15/13
Layer 6 Layer 10
Shower maximum – Layer 8
PS
US
PS
US
PS
US
SNR for 20 GeV Electron
Lucia Bortko | Design studies for BeamCal using new beam parameters | 2013-05-28 | Page 16/13
Layer 5 Layer 9
SNR for 10 GeV Electron
PS
US PS
US
PS
US
Shower maximum – Layer 7
Lucia Bortko | Design studies for BeamCal using new beam parameters | 2013-05-28 | Page 17/13
Charge range estimate
For Diamond sensor pad thickness 300 µm:
- Charge collected from MIP: 2.44 fC
- Maximum charge collected – for shower from 500 GeV electron: 12214 fC
(correspond to about 5000 MIPs)
Diamond GaAs
Distribution of the collected charge per pad for 500Gev electron showers
Lucia Bortko | Design studies for BeamCal using new beam parameters | 2013-05-28 | Page 18/13
Diamond
GaAs
Blue – Uniform Segmentation
Orange - Proportional
Green – Uniform Segmentation
Blue - Proportional
Distribution of the collected
charge per pad for 500Gev
electron showers
