Yellow Report Detector Calorimetry

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General Info and Links

EIC general Yellow Report WG Calorimetry Workshops
Table 1. EIC R&D eRD1 (Calorimetry) talks and reports
Table 2. WG Calorimetry presentations
  • 1. 2020/02/11 WG meeting Introduction E.Chudakov/V.Berdnikov
  • 2. 2020/02/25 WG meeting ECAL Initial consideration A.Bazilevsky
  • 3. 2020/02/25 WG meeting HCAL O.Tsai
  • 4. 2020/03/10 WG meeting W/ScFi Calorimeters C.Woody
  • 5. 2020/03/19 Temple meeting Initial considerations for ECAL A.Bazilevsky
  • 6. 2020/03/19 Temple meeting ECAL technology for EIC T.Horn
  • 7. 2020/03/19 Temple meeting Jet detection B.Page
  • 8. 2020/03/19 Temple meeting HCAL at EIC O.Tsai
  • 9. 2020/03/21 Temple meeting WG Calorimetry summary E.Chudakov
  • 10. 2020/03/30 WG meeting W/ScFi Calorimeters C.Woody
  • 11. 2020/03/30 WG meeting W Shashlyk S.Kuleshov
  • 12. 2020/03/30 WG meeting Questions to WG Conveners
  • 13. 2020/03/30 WG meeting Jets for 3D imaging M.Arratia
  • 14. 2020/04/07 WG meeting ECAL granularity A.Bazilevsky
  • 15. 2020/04/07 WG meeting HCAL high/resolution O.Tsai
  • 16. 2020/04/07 WG meeting ECAL crystals, glass, size V.Berdnikov
  • 17. 2020/04/14 WG meeting BeAST geometry A.Kiselev
  • 18. 2020/05/05 WG meeting 1 page for DAQ group E.Chudakov
  • 19. 2020/05/05 WG meeting DAQ/electronics WG convener talk A.Celentano
  • 20. 2020/05/13 Workplan for EIC ECAL@JLab talk V.Berdnikov
  • 21. 2020/05/19 WG meeting ECAL for eID A.Bazilevsky
  • 22. 2020/05/19 WG meeting CAL summary page WG conveners
  • 23. 2020/05/21 Pavia Workshop ECAL for eID A.Bazilevsky
  • 24. 2020/05/22 Pavia Workshop Calorimetry summary E.Chudakov
  • 25. 2020/05/26 WG meeting Jets for 3D imaging M.Arratia
  • 26. 2020/06/02 WG meeting ECAL for eID / shower profile A.Bazilevski
  • 27. 2020/06/09 WG meeting Comments, action items WG conveners
  • 28. 2020/06/16 WG meeting Integration software A.Kiselev 28a.
  • 29. 2020/06/30 WG meeting ECAL effect on material A.Bazilevsky
  • 30. 2020/07/07 WG meeting Join meeting with PID WG V.Berdnikov
  • 31. 2020/07/14 WG meeting ECAL e-arm simulation M.Bondi
  • 32. 2020/07/14 WG meeting ECAL effect on material (2) A.Bazilevsky
  • 33. 2020/07/28 WG meeting Integration software update A.Kiselev
  • 34. 2020/08/11 WG meeting ECAL depth impact A.Bazilevsky
  • 35. Contribution Sampling ECAL summary C.Woody
  • 36. from DIS 2018 TOPSiDE Concept
  • 37. 2020/08/18 WG meeting TOPSiDE W.Armstrong
  • 38. 2020/08/18 WG meeting Jets for higher resolution HCAL M.Arratia
  • 39. 2020/08/18 WG meeting Need for a preshower in h-endcap? A.Bazilevsky
  • 40. 2020/08/18 WG meeting Preshower option A.Kiselev

Report

Introduction and General Info on Calorimeters

The YR Calorimetry Working Group has been collecting information on existing technologies used in as well as new technologies being developed for electromagnetic (ECAL) and hadron calorimeters (HCAL) and has been evaluating their applicability for the EIC project.

The important parameters of calorimeters are:

  • Energy resolution. The commonly used approximation for a particle of energy E is: σE/E = α ⊕ β/√E ⊕ γ/E. The term γ depends on the noise level and is typically negligible for photosensors with high gains. It is ignored in this study. The constant term α depends on a number of factors, including the calorimeter thickness (on the leakage of showers outside of the calorimeter active area), and also on the quality of the detector calibration. For ECALs with hundreds of channels or more, typically α>1% [1]. The stochastic term β depends on the technology used (the sampling ratio, the size of the signal observed etc.).
  • Position resolution of the particle impact. An approximation used: σx = δ ⊕ ε/√E ⊕ Δ·sin(θ). The resolution depends on the granularity (for ECAL limited by the Molière radius) and the energy resolution. The terms δ and ε are approximately proportional to the cell size, while θ is the angle between the incoming particle trajectory and the cell longitudinal axis. This last term becomes important for a non-projective geometry of the detector. For ECAL Δ≈X0 - the average radiation length of the material [2].
  • Lowest detectable energy Depends on the signal size versus noise and low-energy background.
  • ECAL: electron/pion separation Mostly depend on the energy resolution and the longitudinal segmentation (if any).
  • Detector longitudinal size A denser material allows to make the detector shorter for the given thickness in radiation lengths (ECAL) of interaction lengths (HCAL). The resolution may depend on the thickness.
  • Signal timing: the pulse length. A long signal may affect the signal/noise ratio and the pattern recognition.

A number of technologies have been studied and developed in the framework of the EIC R&D [3]. The WG mostly discussed the technologies addressed in these eRD1.

ECAL

The energy resolution of any calorimeter depends on:

  • Uniformity of the measured response across the volume of the detector (see for example W/ScFi)
  • Shower containment. The dependence of the energy resolution of the calorimeter on its depth in radiation length was addressed in [4]. Typically, a shorter calorimeter provides a higher constant term α. A high resolution (β=2%) calorimeter should be >22RL thick while a medium resolution one (β=12%) may be >18RL thick.
  • Signal size. More photoelectrons/GeV lead to smaller relative fluctuations and a lower impact of noise. A typical yield of a classic lead glass calorimeter is about 1000p.e./GeV providing fluctuations of RMS=3% at 1GeV, to be compared with the factor β. For high resolution calorimeters β<3% the yield should be higher.

The best energy resolution is obtained with homogeneous detectors which produce large signals per MeV absorbed. Scintillating crystals may provide β≃2%.


Table 3. Properties of materials used in homogeneous electromagnetic calorimeters
Material Density, g/cm3 X0, cm RM, cm λI, cm Refr. index τ, ns Peak λ, nm Np.e./GeV ** rad β (σE/E)
PbWO4 [5] 8.30 0.89 1.96 20.3 2.20 5/39%
15/60%
100/01%
420
440
104 106 2.2% *
glass TF1 [6] 3.85 2.8 3.7 38 1.647 Cher Cher 103 103 5.5%
DSB:Ce glass loaded with Gd 4.7-5.4 3.6 3 ~20 - 50/ - %
86/-%
400/ - %
440
460
104 106 (3-4)%
DSB:Ce glass 3.7 2.6 3 ~20 - 22/ - %
72/-%
450/ - %
440
460
104 106 (3-4)%

* β=2.2% for PbWO4 has been obtained with the PMT readout at 18°C (PRIMEX). APD readout at -25°C provided β=3.5% (PANDA).
** Measured with PMTs

Table 3a. Examples of homogeneous calorimeters . The purpose of the table is to demonstrate the typical resolutions obtained in test beams or experiments.
Ref Type cell RL Photo-
sensor
Tempe-
rature
Test beam, GeV matrix Light/signal Yield α β, GeV0.5 γ, GeV δ, mm ε, GeV0.5
mm
GAMS 1995 PbWO4 20×20×180 mm³ 20 PMT XP1911 176mm² 14±0.2°C 10-70 5×5 6 p.e./MeV 0.47±0.06% 2.8±0.2% - - -
KEK 2000 PbWO4 20×20×200 mm³ 22.5 PMT R4125 176mm² 13°C 0.2-1.0 3×3 - 0.0±2.7% 2.5±0.1% 1.4±0.1% 0.4±0.6 2.6±0.1
ALICE PHOS 2005 PbWO4 22×22×180 mm³ 20 APD S8148 25mm² -25±0.1°C 0.6-150 3×3 7.5 p.e./MeV[7] 1.1±0.3% 3.6±0.2% 1.1±0.3% 0.3 2.6
CMS 2006 PbWO4 22²-27²×230 mm³ 26 APD 2×25mm² 18±0.1°C 25-100 3×3 - 0.40±0.03% 2.93±0.21% 12.9±0.2% - -
PRIMEX 2006 PbWO4 20.5×20.5×180 mm³ 20 PMT R4125HA 176mm² 14±0.1°C 1.2-3.5 5×5 - 0.9% 2.5% 1.0% - -
PANDA 2016 2011 PbWO4 21²-27²×200 mm³ 22.5 LAAPD 190mm² shaping ∼1μs -25°C 0.05-0.750 3×3 16 p.e./MeV[8] 0.5% 2.3% 0.27% 2.26±0.05 2.02±0.04
COMPASS 2007 TF1 LG 38×38×450 mm³ 16 PMT FEU-84-3 - 0.5 - 40 5×5 - 1.5% 5.5% - 0.5 6.0

The resolution of sampling detectors may vary β≃5-15% depending on the sampling fraction and the granularity of the active and passive material:

  • Sampling Fraction is the fraction of the total energy released in the active material. For a better resolution one needs a larger sampling fraction, which typically increases the detector length for the same thickness in RL.
  • Sampling frequency is related to the thickness of one "layer" of the absorber and the active material (scintillator). This parameter is well defined for the "sandwich"-type geometry. The energy resolution gets worse for the thickness >0.25X0.

GEANT calculations [9] show the dependence of the resolution on the sampling frequency and on the calorimeter depth for a W/Sc shashlyk calorimeter. R.Wigmans et al [10] argues that the stochastic coefficient β is proportional to √(d/SF), where d is the thickness of the active material layer (or a fiber).

Table 4. Info on sampling electromagnetic calorimeters (ordered by the mean radiation length of the material)
Type Structure Sampling Fraction* Density, g/cm3 X0, cm RM, cm λI, cm τ, ns Peak λ, nm Np.e./GeV rad β (σE/E)
#1 Shashlyk W/SC/WLSF HERA-B[11] (W/Fe(90/10) 2.2mm Sc 1.0mm) 4% 12.4 0.56 1.24
1.35
19 12 500 - >106 20%**
#2 W powder/ScFi sPHENIX[12] ⌀0.47mm ScFi/mm² + W powder 2% 9 0.7 2.0
1.9
20. 2.8 450 - 106 13-15%
#3 Shashlyk W/SC/WLSF eRD1[13] (W/Cu(80/20) 1.58mm Sc 1.63mm) 9% 9.0 0.83 1.9 15 12 500 - 106 8%**
#4 W powder/ScFi[14]
PMT reaout
0.59×0.59mm² ScFi/0.82mm² + W powder 12% 5.9 1.31 2.8 28. 2.8 450 - 106 7-8%
#5 Shashlyk Pb/SC/WLSF COMPASS [15] (Pb 0.8mm Sc 1.55mm) 23% 4.4 1.64 3.5 36 12 500 - 106 6%
#6 Shashlyk Pb/SC/WLS LHCb[16] (Pb 2mm Sc 4mm) 24% 4.4 1.66 3.5 38 12 500 3p.e./MeV 106 9.4%
#7 Shashlyk Pb/SC/WLS PHENIX[17] (Pb 1.5mm Sc 4mm) 28% 3.8 2.0 4.2 43 12 500 1.5p.e./MeV 106 8%
#8 Shashlyk Pb/SC/WLSF NICA[18] (Pb 0.3mm Sc 1.5mm) 50% 2.6 3.3 6.2 52 12 500 5 pxs/MeV 106 4.5%
#9 Shashlyk Pb/SC/WLSF PANDA[19] (Pb 0.275mm Sc 1.5mm) 50% 2.6 3.4 5.9 52 12 500 5 pxs/MeV 106 3.0%

* Sampling Fraction is the fraction of the total energy released in the active material
** Calculation only

The W/ScFi and Shashlyk calorimeters may have a significant non-uniformity of the response depending on the particle impact position and angle, because the fibers orientation is more or less along the partice trajectories. The best results was obtained with the "spiral fibers" (see Table.4 #5). However, the technology is complex in manufacturing and assembling.


Table 4a. Examples
Ref Type
SF#
Structure
full length*
RL cell Photosensor Tempe-
rature
Test beam, GeV matrix Light/signal Yield α β, GeV0.5 γ, GeV δ, mm ε, GeV0.5
mm
PHENIX 2003 Shashlyk 28% (Pb 1.5mm Sc 4.0mm)×66
≈47cm
18 55.3×55.3mm² 36WLSF PMT FEU115M 200mm² - 5-80 3×3 1500p.e./GeV 2.1% 8.1% - 1.55 5.7
HERA-B 2007 Shashlyk
20%
(Pb 3mm Sc 6.0mm)×37
≈41cm
20 55.9×55.9mm² 36WLSF PMT FEU84-3 - 5-28 3×3 800p.e./GeV 1.4±0.1% 11.9±0.2% - 2.8±0.2 13.7±0.3
HERA-B 2007 Shashlyk
4%
(W/Fe(90/10) 2.2mm Sc 1.0mm)×40
≈20cm
23 22.3×22.3mm² 9WLSF PMT FEU68 - 5-28 3×3 130p.e./GeV 1.2±0.2% 20.6±0.3% - 2.2±0.3 12.5±0.3
KOPIO 2008 Shashlyk
54%
(Pb 0.275mm Sc 1.5mm)×300
≈110cm
16 110×110mm² 144WLSF APD API 200mm² 18±0.2°C 0.22-0.37 3×3 50 p.e./MeV 2.0±0.1% 2.74±0.05% - - -
PANDA 2009 Shashlyk
54%
(Pb 0.275mm Sc 1.5mm)×380
≈110cm
20 110×110mm² 144WLSF PMT R5800 200mm² - 1-19 3×3 5 p.e./MeV 1.30±0.04% 2.8±0.2% 3.5±0.3 3.3±0.1 15.4±0.2
COMPASS 2005? Shashlyk spiral
21%
(Pb 0.8mm Sc 1.55mm)×156
45cm
23 38×38mm² 16WLSF PMT FEU-84-3 - 1.0-7.0 ? 3×3 - - 5.5% - - -
COMPASS-II 2015 Shashlyk
20%
(Pb 0.8mm Sc 1.5mm)×109
34cm
16 40×40mm² 16WLSF MAPD 135kpx 9mm² 16±?°C 1.0-7.0 3×3 - 2.3% 7.8% - - -
COMPASS-II 2019 Shashlyk
20%
(Pb 0.8mm Sc 1.5mm)×109
34cm
16 40×40mm² 16WLSF MPPC 90kpx 9mm² nonlinear! 16±?°C 1.0-30.0 3×3 - 1.4%·E0.25 7.1%·(1+0.06/E) - - -
LHCb 2008 Shashlyk
19%
(Pb 2mm Sc 4mm)×66
≈53cm
24 40×40mm² 16WLSF PMT R7899 - 5-100 3×3 3000 p.e./GeV 0.83±0.02% 9.4±0.2% 14% - -
ALICE EMCal 2011 2010 Shashlyk
9.5%
(Pb 1.44mm Sc 1.76mm)×77
≈40cm
20 60×60mm² 36WLSF APD S8664-55 - 0.5-100 3×3 4400 p.e./GeV 1.7±0.3% 11.3±0.5% 4.8±0.8% 1.5 5.3
MPD NICA 2019 Shashlyk
50%
(Pb 0.3mm Sc 1.5mm)×220
≈48cm
12 40×40mm² 16WLSF MPPC 13360-6025 36mm² - 0.5-3
0.05-0.3
3×3 5000 p.e./GeV 1.0±0.3%
2.4±0.4%
4.4±0.4%
2.8±0.1%[20]
- - -
sPHENIX 2020 W/ScFi
2%
⌀0.47mm ScFi + W powder
15cm
20 25×25mm² 666 ScFi 4 MPPC S12572-015P 9mm² 120k pixels total - 2-28 3×3 300 pxs/GeV 3.0±0.1% 15.4±0.3% - - -

# SF - sampling fraction
* Full length up to the photosensor

HCAL

Hadron calorimeters technologies and application to EIC has been addressed in several presentations [21]. For a number of reasons the preference is given to a Iron/Scint sandwich with a WLS bar at a side for readout. The resolution depends on the thickness of the calorimeter. A 1m-thick calorimeter can provide β=50% and α=10%.

Readout considerations

Only detectors with optical readout have been considered. In the current scenarios the endcap ECAL photosensors will be located in a magnetic field of >0.1T, which precludes the usage of regular PMTs. The barrel ECAL is located in a >1T field. At the moment the sensor of choice is SiPM, which provides a high gain (about 106) and a medium photodetection efficiency of about 20%. The drawbacks are noise, small surface, sensitivity to neutron/proton radiation, sensitivity to temperature, a small dynamic range, and the intrinsic nonlinearity [22]. Radiation leads to a higher noise. For the same size of the light source SiPM can fire a number of pixels comparable to a PMT photoelectron count[23]. However, a fraction of the pixels fire due to the cross talk, not improving the statistical fluctuations. While a SiPM readout is natural for the fiber technologies as Shashlyk, it is not useful for a large-surface - 16cm2 - glass blocks. It has not been tested yet with 4cm2 crystals. The readout of endcap HCAL will be located in a smaller field. If iron is used for the absorber the field is low enough for PMTs.

The effect of non-linearity for SiPMs depends on the desired dynamic range and the calorimeter resolution. Let us consider the requirements of a 2% energy resolution at 1GeV and the maximum energy of 20GeV (the center of the e-arm). The p.e. (or pixel) count at 1GeV should be ≳10k (1% statistical fluctuations). Then, at 20GeV the pixel count with no saturation would be about 200k. A NICA module (see the TDR) has been tested with a Hamamatsu MPPC S13360-6025 which contains 57k pixels 25×25μm². With the yield of about 5000pxs/GeV the loss to non-linearity at 2GeV was about 10%. With 4 such sensors and 10000pxs/GeV the signal at 20GeV will be 66% of the linear extrapolation. The SiPM response should be calibrated to a 1% level which may be not trivial.

EIC requirements

In EIC experiments the calorimeters are needed for their usual tasks:

  • Detect neutral particles - gammas and neutrons.
  • Detect scattered electrons in ECAL in order to improve the energy/momentum resolution at large |η|
  • PID with ECAL: separate electrons and positrons from charged hadrons
  • Help with identification of jets

The physics requirements to the EIC detector system including the calorimeters are specified in the Interactive Detector Matrix. For the calorimeters the matrix originally specified only the required energy resolution, namely the stochastic term β.

The kinematic range and the requirements for the electron detection in ECAL was discussed at length in presentations [24]. The photon detection was also addressed there.

The requirements to HCAL coming from jet physics were discussed in presentations [25]. The physics working groups assume that HCAL has the 4π coverage.

Figure 1: Tentative EIC spectrometer layout from 2020 Jul 18

A practical limitation on possible choices of technologies comes from the space allocated for the EIC calorimeters. A layout of the spectrometer from the presentation by M.Breitfeller at the 1st YR Workshop ("Temple meeting") was first considered. In that design the hadron arm has ΔZ=87 cm allocated for HCAL and 38 cm for ECAL. The electron arm is the same, though there is no obvious obstacle for an extension toward the center of the magnet. A newer layout from a presentation by A.Kiselev (Maiami 2020 Jul) (see Fig.1) provides more space in the electron arm (ΔZ=50 cm) and is taken for guidance. The barrel calorimeter depends on the magnet design. For the BaBar magnet the outer diameter of ECAL can go up to 140 cm, while the minimal radial thickness of ECAL is about 30 cm (based on the sPHENIX experience).

At present, the conclusion is that technologies exist that meet (or nearly meet) the requirements as specified in the matrix. A selection of technologies that can fit into a given longitudinal space are listed below. Note that there are additional requirements on the technologies that have to be fulfilled depending on detector region.

Apart of the energy resolution the group has considered other characteristics of the proposed system and has studied various effects:

  • The spatial resolution - studied by simulation. The results match several measurements for similar detectors.
  • The e-- separation. The effect was discussed with the PID DWG and with physics groups [26]. It was concluded that other detectors may be needed to provide an additional e-- separation at energies <3 GeV.
  • The single photon versus π0 separation.
  • The impact of the material in front of ECAL on the performance [27]. At |η|>2 and p<10GeV the impact is significant.
  • Projectivity of ECAL modules: assumed for the barrel, but in question for the endcaps
Table.5 Calorimetry for EIC
η ECAL HCAL
Total depth, cm Depth, RL Energy resolution σE/E, % Spacial resolution σX, mm Granularity, mm2 Min. photon energy, MeV PID e/π, π suppression Technology examples* total depth, cm Energy resolution σE/E, % Spacial resolution σX, mm Granularity, mm2 Technology examples
-4.0:-2.0 38 22 1.0⊕2.2/√E⊕1.0/E 3/√E⊕1 20×20 20 1000 PbWO4 crystals 105 50/√E⊕10 50/√E⊕30 100×100 Fe/Sc
-2.0:-1.0 38
38
50
50
(65)**
20
20
22
13*
16*
1.5⊕8.0/√E⊕2/E
2⊕12/√E⊕2/E
1.5⊕(7-8)/√E⊕2/E
 ?
1.5⊕4.0/√E⊕2/E
3/√E⊕1
3/√E⊕1
6/√E⊕1
6/√E⊕1
6/√E⊕1
25×25
25×25
40×40
40×40
40×40
50
50
50
30
30
300 W/Sc Shashlyk
W powder/ScFi
Pb/Sc Shashlyk
SciGlass
SciGlass
105 50/√E⊕10 50/√E⊕30 100×100 Fe/Sc
-1.0:1.0 30
30
38
65 *
18
18
22
16*
2⊕12/√E⊕2/E
3⊕14/√E⊕2/E
1.0⊕2.2/√E⊕1.0/E
1.5⊕4.0/√E⊕2/E
3/√E⊕1
3/√E⊕1
3/√E⊕1
6/√E⊕1
25×25
25×25
20×20
40×40
100
100
20
30
300
300
1000
300
W/Sc Shashlyk
W powder/ScFi
PWO
SciGlass
110 100/√E⊕10 50/√E⊕30 100×100 Fe/Sc
1.0:4.0 38
38
(50)**
(65)**
20
20
22
16*
1.5⊕8.0/√E⊕2/E
2⊕12/√E⊕2/E
1.5⊕10.0/√E⊕2/E
1.5⊕4.0/√E⊕2/E
3/√E⊕1
3/√E⊕1
6/√E⊕1
6/√E⊕1
25×25
25×25
40×40
40×40
100
100
100
30
300 W/Sc Shashlyk
W powder/ScFi
Pb/Sc Shashlyk
SciGlass
105 50/√E⊕10 50/√E⊕30 100×100 Fe/Sc

* A non-PMT readout is assumed, occupying <15cm longitudinally
** If more space than in the current layout is allocated
*** Additional technologies may be considered


Simulations

https://inspirehep.net/literature/892265
Table.6 Simulation studies status
Calorimeter Region Simulation type Status Link
PbWO4 Backward Escalade + GEMC Active Mariangela Bondi
glass TF1 Backward
DSB:Ce scintillating glass Backward Escalade + GEMC Active Mariangela Bondi
Fe/Sc HCAL Backward Geant4 Active Oleg Tsai
Shashlik Backward Geant4 standalone
Fun4All
Active Vasilii Mochalov
Craig Woody
W/SciFi Barrel Fun4All Active Craig Woody
Scintillating glass Barrel Escalade Active Mariangela Bondi
Fe/Sc HCAL Barrel Geant4 standalone Active Oleg Tsai
W/SciFi Forward Fun4All Active Craig Woody
Shashlik Forward Geant4 Standalone
Fun4All
Active Vasilii Mochalov
Craig Woody
DSB:Ce Scintillating glass Forward Escalade+GEMC Active Mariangela Bondi
Glass TF1 Forward
Fe/Sc HCAL Forward Geant4 Standalone Active Oleg Tsai

Appendix

  • Endcap ECAL ΔZ<38 cm:
    • PbWO4 crystals: The technology is mature with additional R&D subject of EIC eRD1 (see the eRD1 reports) - several large detectors have been in operation, e.g. the Jefferson Lab CLAS inner calorimeter, HPS, CLAS12 forward tagger, HyCal, and NPS (arxiv). The typical resolution obtained at 18°C and with the PMT readout is β≈2.3%. A better light yield and a better resolution can be achieved at lower temperatures <5°C, but lower temperatures also impact radiation hardness and recovery (see EIC rRD1, NPS, CLAS12 forward tagger, and PANDA studies).
    • W powder + scint. fibers: technology developed for sPHENIX (see a summary), α=3% β=13-14%, with a SiPM readout. The resolution is limited by the non-uniformity inherent to the design.
    • W/Sc shashlyk: technology not yet demonstrated, but appears possible based on the developed Pb/Sc shashlyk technology. For the latter β≈10% is common, while β≈7% is challenging but has been achieved. Simulation for W/Sc shashlyk produced β≈8%. SiPM readout should not be a problem.
  • Endcap ECAL ΔZ<50 cm:
    • Scintillating glass: technology is actively under development as part of eRD1 (see EIC eRD1 reports). Compared with typical lead glass the expected light yield is an order of magnitude higher, while the radiation length is largely comparable. The scintillating glass is radiation hard under EM (tested to 10000 Gy) and hadron radiation (tested up to 10^15p/cm2), which is not the case for lead glass. Potentially, the resolution may reach β=3-4%. A more compact scintillating glass length of Z=25-30cm may be possible if higher resolution is acceptable. The optimal size of the photo sensor compared with the cell transverse size needs to be investigated. SiPM readout should not be a problem.
    • Pb/Sc shashlyk: technology is mature, with β=7-10%. SiPM readout should not be a problem.
  • Barrel ECAL ΔR<30 cm:
    • W powder + Sc. fibers: technology developed for sPHENIX, α=3% β=13-14%, with a SiPM readout. The resolution is limited by the non-uniformity inherent to the design.
    • W/Sc shashlyk: technology not yet demonstrated, but appears possible based on the developed Pb/Sc shashlyk technology. For the latter β≈10% is common, while β≈7% is challenging but has been achieved. SiPM readout should not be a problem.
  • Endcap HCAL ΔZ<105 cm
    • Fe/Sc: technology exists for β≈50%. Shorter longitudinal space will affect the resolution.
  • Barrel HCAL:
    • a Fe/Sc calorimeter has been developed for sPHENIX. The iron absorber is used for the magnetic flux return of the solenoid. The resolution is about β≈100%.



Calculations of the average parameters of composite structures

It has been notices that different papers sometimes give different numbers for the Molière radius of the same material. In order to treat different matials uniformly we recalculated the value of the radius using the same method. Calculation of the average density and radiation length of a composite structure is straightforward, knowing the composition, say by volume. For the Molière radius a prescription from PDG is used:
RM[g/cm²]=21MeV/∑(wiEi/Xi[g/cm²]), where wi is the fraction of the material by mass, Xi is the radiation length in g/cm², Ei - is the critical energy in MeV.
or
RM[cm]=21MeV/∑(viEi/Xi[cm]), where vi is the fraction of the material by volume, Xi is the radiation length in cm, Ei is the critical energy in MeV.

Table 7. Properties of materials used in calculations
Material Z A Composite Density,
g/cm3
X0, cm Ecrit, MeV RM, cm
by mass by volume published calculated
W 74 184 19.3 0.35 7.97 0.93 0.93
Pb 82 207 11.4 0.56 7.43 1.60 1.60
Cu 29 64 8.96 1.44 18.8 1.57 1.61
Fe 26 56 7.87 1.76 21. 1.72 1.76
Polystyrene, scint. 1.03 42.4 82. 10.8
Epoxy 1.25 34. 82. 8.6
Shashlyk HERA-B
2.2mm W/Fe 90/10;
1mm Sc.
W 62.1%
Fe 6.9%
Sc/plastic 31%
16.0 0.558 - 1.25 1.35
W/ScFi sPHENIX W 43%
Sc 28.5%
Epoxy 28.5%
9. 0.7 - 2.00 1.90
Shashlyk eRD1
1.58mm W/Cu 80/20;
1.63mm Sc.
W 39.4%
Fe 9.6%
Sc/plastic 51%
9.0 0.83 - - 1.9
Shashlyk example 1
0.75mm W/Cu 80/20;
1.55mm Sc.
W 26%
Fe 6.5%
Sc/plastic 67.5%
6.3 1.24 - - 2.6
W/ScFi eRD1,
square fibers
85.8% W
7.5% Sc
6.7% epoxy
W 26%
Sc 42.6%
Epoxy 31.4%
5.9 1.31 - - 2.80
Shashlyk COMPASS
0.8mm Pb;
1.55mm Sc.
Pb 34%
Sc/plastic 66%
4.45 1.64 - 3.5 3.63
Shashlyk PHENIX
1.5mm Pb;
4mm Sc.
Pb 27%
Sc/plastic 73%
3.83 2.0 - 4.2 4.2
Shashlyk PANDA
0.275mm Pb;
1.5mm Sc.
0.05mm plastic
Pb 15%
Sc/plastic 85%
2.58 3.5 - 5.9 5.8

References

  1. α=1.85% for the BaBar CsI 10k channels calorimeter: B.Aubert et al. NIMA 479,1 (2002)
  2. Spacial resolution page 527 PHENIX NIMA 499 (2003) 521)
  3. eRD1 Report-June-2020 Progress-report-Jan-2020
  4. ECAL depth Ref.1
  5. PbWO4 Material properties PDG Some references
  6. TF1 glass see for example PHENIX NIMA 499, 521 (2003)
  7. PHOSN p.e. measured 0.511MeV γ with a PMT, NIMA 486,121 (2002)
  8. PANDA N p.e. IEEE_TNS_55_1295_2008
  9. eRD1 2020 july talk, page 12
  10. Sampling dependence Wigmans et al ppnp.2018.07.003 2018, page 119
  11. W Shahlyk HERA-B 2007
  12. W/ScFi Ref.1 Ref.2 Ref.3 arXiv 2003.13685 eRD1 report Jul 2016
  13. W Shahlyk Ref.1 Ref.2 Ref.3Ref.4 Ref.5
  14. W/ScFi high resolution eRD1 report Jul 2016
  15. Pb Shahlyk COMPASS spectrometer spiral shashlyk 23X0, PMT readout New COMPASS design
  16. Pb Shashlyk LHCb, PMT readout IEEE Trans.Nucl.Sci. 57 (2010) 3, 1447 Nucl.Instrum.Meth.A 348 (1994) 74-86
  17. Pb Shashlyk , PMT readout Nucl.Instrum.Meth.A 499
  18. Pb Shahlyk 1 2 MPD NICA 12X0, SiPM readout
  19. Pb Shahlyk [1]0, PMT readout
  20. MPD shashlyk JINST 15 (2020) 05, C05017
  21. HCAL Ref.1 Ref.2 Ref.3
  22. SiPM linearity for example NIMA 936,141 (2019)
  23. SiPM-PMT comparison NIMA 628, 369 (2011)
  24. Electron detection in EIC Ref.1 Ref.2 Ref.3 Ref.4
  25. Jet Physics and HCAL Ref.7 Ref.13 Ref.24
  26. e/π separation Ref.25
  27. Effect of the material Ref.28 Ref.31