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Ioan DafineiRegional Centre ECAL-CMS Rome ITALY
Villa Olmo, Como 15-19 October 2001
Advanced Technology and Particle Physics
Lead Tungstate Crystals for the CMS Electromagnetic Calorimeter at the LHC
Ioan DafineiI.N.F.N. Sezione di Roma, Rome ITALY
(on behalf of CMS ECAL Collaboration)
Ioan DafineiRegional Centre ECAL-CMS Rome ITALY
Villa Olmo, Como 15-19 October 2001
Advanced Technology and Particle Physics
Index
1. Introduction
2. PWO General Properties
- Luminescence Spectrum
- Scintillation characteristics
- Radiation hardness
3. PWO for ECAL-CMS
- R&D Short Review
- Requisites & Qualification Parameters
- Regional Centers
4. Preproduction Crystal Properties Present Status
5. Recent Developments in PWO Crystal Growth Technology
6. Conclusions
Ioan DafineiRegional Centre ECAL-CMS Rome ITALY
Villa Olmo, Como 15-19 October 2001
Advanced Technology and Particle Physics
Introduction
Requirements for scintillators to be used for ECAL construction
ECAL-CMS
high density and high Z
• mechanical ruggedness• chemical stability• uniformity of properties• low price
small X0
small Rm
large LY
short dead time fast
radiation hard
technological requirements
high stopping power
high granularity
high energy resolution
LHC
Luminosity 1034 cm-2·s-1
Bunch separation 25 ns
emission spectrum overlapping with spectral sensitivity of commonly used photodetectors
high refractive
index
Ioan DafineiRegional Centre ECAL-CMS Rome ITALY
Villa Olmo, Como 15-19 October 2001
Advanced Technology and Particle Physics
Workshop on tungstate crystals
0
20
40
1992 1993 1994 1995 1996 1997 1998 1999 2000 2001
PWO propertiesPWOusersPWO+Othertotal
ArticleStatistics.QPC
SCINT Conferences
Introduction
Studied as scintillator since 1979PbWO4 (PWO)
(g/cm3) 8.26
X0 (cm) 0.89
Rm (cm) 2.2
(ns) 15
emission 420
n@emission 2.29
LY 2 %
LYtemp.coeff. -2%/°C
Ioan DafineiRegional Centre ECAL-CMS Rome ITALY
Villa Olmo, Como 15-19 October 2001
Advanced Technology and Particle Physics
Bridgman method
Shanghai Institute of Ceramics, China
PWO General Properties
PWO Crystal Growth
Chang, 1971
1100
1000
900
800
700
20 40 60 80
mole %
WO3PbO
Liquid
16.5%
37%
66.5%
1123°
970°
740°
915°935°
730°
2:1
1:1
PWO4PWO3
seed
grown crystal
molten PWO
RF heating
Czochralski method
Bogoroditsk Techo Chemical Plant, Russia
Ioan DafineiRegional Centre ECAL-CMS Rome ITALY
Villa Olmo, Como 15-19 October 2001
Advanced Technology and Particle Physics
LumSpectra-B+G.QPC
PWO1168
LumSpectra-green.QPC
green component
PWO1180
0
0.2
0.4
0.6
0.8
1
1.2
300 400 500 600 700
inte
nsi
ty (
a.u
.)
wavelength (nm)
295 K
LumSpectra-blue.QPC
blue component
PWO1185
PWO General Properties
Luminescence Spectrum
a
c WO42-
Pb2+
a
c
WO43-
(MoO4) 3-
a
c (WO6) 6-
Ioan DafineiRegional Centre ECAL-CMS Rome ITALY
Villa Olmo, Como 15-19 October 2001
Advanced Technology and Particle Physics
PWO General Properties
Scintillation Characteristics
Itot
I(t)=0.5·exp(-t/3ns)+0.07·exp(-t/12ns)+0.008·exp(-t/102ns)
101
102
103
0 50 100 150 200 250 300 350
decay data3exp fittrue background
coun
ts per ch
ann
el
time (ns)DecayIntegral.QPC
Iss
=100·(Iss/Itot) (%)
Spectrally unresolved scintillation
10-6
10-5
10-4
10-3
10-2
10-1
100
10-8 10-7 10-6 10-5
emision@400 nmemision@500 nmlaser pulse
inte
nsi
ty (
a.u.
)
time (s)LumLaserExc.QPC
exc=308 nm (XeCl excimer laser)
Photoluminescence decay
Ioan DafineiRegional Centre ECAL-CMS Rome ITALY
Villa Olmo, Como 15-19 October 2001
Advanced Technology and Particle Physics
PWO General Properties
Scintillation Characteristics
0
200
400
600
800
1000
1200
1400
-200 -150 -100 -50 0 50
lig
ht
yield
(a.u
.)
temperature (°C)
20°C = -1.98%/°CI.Dafinei, Mat.Res.Soc. Vol.348(1994), p.99
50
100
150
200
250
300
-5
-4
-3
-2
-1
0
-20 0 20 40 60-40
lig
ht
yield
(a.u
.)
temperature (°C)
tem
p.c
oeff
.(%
/°C
)
Ioan DafineiRegional Centre ECAL-CMS Rome ITALY
Villa Olmo, Como 15-19 October 2001
Advanced Technology and Particle Physics
0
20
40
60
80
300 400 500 600 700 800
tran
smis
sio
n (
%)
wavelength (nm)
undoped
La-doped
295 K
RadHard.QPC
PWO General Properties
Radiation Hardness
0
1
2
3
300 500 700 900
ind
uc
ed
ab
so
rpti
on
(m
-1)
wavelength (nm)
undoped
La-doped
•light production is not affected
•creation of color centres is quenched by appropriate doping
Ioan DafineiRegional Centre ECAL-CMS Rome ITALY
Villa Olmo, Como 15-19 October 2001
Advanced Technology and Particle Physics
R&D Short Review
• 1992 : Crystal2000 Conference• 1994 : choice of PWO for CMS-ECAL• 1994-1998 : R&D phase
0
20
40
60
80
100
300350 400 450500 550600650700
Tra
nsm
issi
on
(%
)
Wavelength (nm)
Theoretical transmission
'95 crystal
'98 crystal
• 1998-2000 : Pre-Production of 6000 crystals• 2001 : Start of the Production
1995 1998
Ioan DafineiRegional Centre ECAL-CMS Rome ITALY
Villa Olmo, Como 15-19 October 2001
Advanced Technology and Particle Physics
R&D Short Review
Goals of Pre-production Activity
For Producer : Increase the rate of production Improve the crystal quality and homogeneity of properties
For CMS-ECAL communitySetting up the Regional Centres Installation of Automatic Crystal Control System (ACCOS) (machines designed to make the full characterisation of 30 crystals in 7 hours)
All the 6000 crystals have been measured on ACCOS at CERN
800 re-measured on ACCOR at Rome (ACCOS-ACCOR intercalibration)
Ioan DafineiRegional Centre ECAL-CMS Rome ITALY
Villa Olmo, Como 15-19 October 2001
Advanced Technology and Particle Physics
Requisites & Qualification Parameters
Qualification parametersLight Yield
• LY@8X0 8 pe/MeV at 18°C
• -0.35 %/X0 FNUF +0.35 %/X0
• LY(100ns)/LY(1s) > 90%
LY@8X0 =7.5·a+b
FNUF =100·(-0.89·a)/(11.5·a+b)
LY(x)= a · x+b
Ioan DafineiRegional Centre ECAL-CMS Rome ITALY
Villa Olmo, Como 15-19 October 2001
Advanced Technology and Particle Physics
Requisites & Qualification Parameters
Qualification parametersTransmission
•LT360nm 25%
•LT420nm 55%
•LT620nm 65%
•LTslopeinflection > 3%/nm
TT=50% 3nm
0
20
40
60
80
300 400 500 600 700
LT1535557595115135155175195215
Tra
ns
mis
sio
n (
%)
wavelength (nm)PWO1713_Ro.QPC
TTLT
Check general quality and radiation resistance
LT
TT
T=p2·exp(-(p3)/w-exp((p0-w)·p1))
Ioan DafineiRegional Centre ECAL-CMS Rome ITALY
Villa Olmo, Como 15-19 October 2001
Advanced Technology and Particle Physics
•dimensions within +0.00 mm , -0.10 mm of nominal values
•planarity for all faces within 0.02 mm
•chamfers between 0.3 mm and 0.7 mm
•polished faces with roughness < 0.020 m
•unpolished face with roughness = 0.350 m
ECAL-CMS
Requisites & Qualification Parameters
Qualification parametersDimensios !
Ioan DafineiRegional Centre ECAL-CMS Rome ITALY
Villa Olmo, Como 15-19 October 2001
Advanced Technology and Particle Physics
Regional Centers
CERN Lab.27 Regional Center
Dimensions
Light yield uniformity
Transmission
ACCOCE http://cmsdoc.cern.ch/cms/ECAL/html/wp/rc/
CERN Lab.27 EP-CMA
Ioan DafineiRegional Centre ECAL-CMS Rome ITALY
Villa Olmo, Como 15-19 October 2001
Advanced Technology and Particle Physics
Regional Centers
Rome, Italy Regional Center http://www.roma1.infn.it/exp/cms/
Casaccia
Co60
PM
LED
Light yield uniformity
Dimensions
Coord3 S.p.A.
Dark roomtemperature : 20±0.5°C rel. humidity: 50±10%
ACCOR
Capacity:35 crystals/run1 run time:approx. 10 hours Transmission
Ioan DafineiRegional Centre ECAL-CMS Rome ITALY
Villa Olmo, Como 15-19 October 2001
Advanced Technology and Particle Physics
Regional Centers
ACCOS-ACCOR Intercalibration
Measure 2-3 pe !
LY>8pe/MeV
R-C=0.8pe/MeV
R-C=0.19%/Xo
-0.35<FNUF(%/Xo)<+0.35
Ioan DafineiRegional Centre ECAL-CMS Rome ITALY
Villa Olmo, Como 15-19 October 2001
Advanced Technology and Particle Physics
Regional Centers
ACCOS-ACCOR Intercalibration
LT@360nm
0
10
20
30
40
50
60
0 10 20 30 40 50 60RomeLT@360
Cer
nL
T@
360
60
65
70
75
60 65 70 75
LT@420nm
RomeLT@420
Cer
nL
T@
420
RomeLT@620
Cer
nL
T@
620
65
70
75
80
65 70 75 80
LT@620nm
R-C=1.4% R-C=0.8% R-C=0.5%
Ioan DafineiRegional Centre ECAL-CMS Rome ITALY
Villa Olmo, Como 15-19 October 2001
Advanced Technology and Particle Physics
Regional Centers
ACCOS-ACCOR Intercalibration
R-C=0.15%/nm
0
0.5
1
1.5
2
2.5
3
3.5
4
0 0.5 1 1.5 2 2.5 3 3.5 4
Ro
ma
TT
sp
(n
m)
Cern TTsp (nm)
TT spread at 50%
Inflection Wavelength
345
349
353
357
359
345 349 353 357Rome
Cer
n
2
2.5
3
3.5
4
2 2.5 3 3.5 4
Rome S@infl (%/nm)
Cer
n S
@in
fl (
%/n
m)
Rad hard check
LT slope@inflection
R-C=0.15%/nm
Ioan DafineiRegional Centre ECAL-CMS Rome ITALY
Villa Olmo, Como 15-19 October 2001
Advanced Technology and Particle Physics
Regional Centers
ACCOS-ACCOR Intercalibration
Statistics made on 373 Xtals
CF
AF
BFCR
AR
BR
229.5
230
230.5
229.5 230.0 230.5
L@
Ro
ma
(m
m)
L@CERN (mm)
L
21.5
21.75
21.50 21.75
AF
@R
om
a
(mm
)
AF@CERN (mm)
AF
22.4
22.6
22.8
22.40 22.60 22.80
BF
@R
om
a
(mm
)
BF@CERN (mm)
BF
21.6
21.8
22.0
22.2
21.6 21.8 22.0 22.2
CF
@R
om
a
(mm
)
CF@CERN (mm)
CF
Ioan DafineiRegional Centre ECAL-CMS Rome ITALY
Villa Olmo, Como 15-19 October 2001
Advanced Technology and Particle Physics
Pre-Production Crystal Properties
Wavelength (nm)
0102030405060708090100
300 350 400 450 500 550 600 650 700
Lon
git
ud
i nal
Tra
nsm
i ssi
on
(%
)
0
200
400
600
800
1000
1200
1400
30 35 40 45 50 55 60 65 70 75 80
Transmission at 420nm (%)
6000 crystals
no.o
f X
tals
55%
0
2
4
6
8
10
30 35 40 45 50 55 60 65 70 75 80
Nu
mb
er
of
cry
stals
Transmission at 420nm (%)
Mean: 61.88%StDev. : 7.5%batch 1
0
50
100
150
200
250
30 35 40 45 50 55 60 65 70 75 80Transmission at 420nm (%)
Mean: 69.01%StDev. : 1.59%
batch 8
Transmission at 420nm (%) 11.04.01
Mean: 70.07%
StDev. : 1.46%
0
50
100
150
30 35 40 45 50 55 60 65 70 75 80
batch 14
Ioan DafineiRegional Centre ECAL-CMS Rome ITALY
Villa Olmo, Como 15-19 October 2001
Advanced Technology and Particle Physics
Pre-Production Crystal Properties
0
2
4
6
8
10
12
14
16
18
20
0.2 2.2 4.2 6.2 8.2 10.2TTspread@50% (nm)
# cr
ysta
ls
0
5
10
15
20
25
30
35
40
0.1 1.1 2.1 3.1Slope@infl (%/nm)
# cr
ysta
ls
Pre-Production in China
0 10 20 30 40 50 60 70 80LT@360nm (%)
0
2
4
6
8
10
12
14
16
18
# c
rys
tals
0
2
4
6
8
10
12
14
16
# cr
ysta
ls
0 10 20 30 40 50 60 70 80LT@420nm (%)
0
5
10
15
20
25
30
35
40
45
# cr
ysta
ls
0 10 20 30 40 50 60 70 80LT@620nm (%)
Transmission characteristics
Statistics madeon 100 crystals
Ioan DafineiRegional Centre ECAL-CMS Rome ITALY
Villa Olmo, Como 15-19 October 2001
Advanced Technology and Particle Physics
Pre-Production Crystal Properties
Batch 1 to 7 <Ra> depolished face +0.2
Batch 8 to 14 <Ra> depolished face +0.39
0
200
400
600
800
1000
1200
-1.5 -1 -0.5 0 0.5 1 1.5 2NuF Front (%/Xo)
FNUFLY@8X0
0
200
400
600
800
1000
1200
1400
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16LY@8X0 (pe/MeV)
0
50
100
150
200
250
300
350
-1.5 -1 -0.5 0 0.5 1 1.5 2NuF Front (%/Xo)
FNUF
0
100
200
300
400
500
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16LY@8X0 (pe/MeV)
LY@8X0
Ioan DafineiRegional Centre ECAL-CMS Rome ITALY
Villa Olmo, Como 15-19 October 2001
Advanced Technology and Particle Physics
Pre-Production Crystal Properties
LY@8X0 (ACCOS measured)
0
5
10
15
20
25
30
35
0 2 4 6 8 10 12 14 16
LY (p.e./MeV)
# cr
ysta
ls
Pre-Production in China
Light production characteristics
Statistics madeon 100 crystals
Ioan DafineiRegional Centre ECAL-CMS Rome ITALY
Villa Olmo, Como 15-19 October 2001
Advanced Technology and Particle Physics
Pre-Production Crystal Properties
Front irrad., 1.5Gy, 0.15Gy/h
90
95
100
105
0 0.5 1 1.5 2 2.5
Low dose rate irradiation of some BTCP crystals of Batch06 in lab27
PWO4510 (%LY)
PWO4579 (%LY)
PWO4585 (%LY)
PWO4590 (%LY)
PWO4622 (%LY)
PWO4623 (%LY)
PWO4533 (%LY)
PWO4481 (%LY)
PWO4473 (%LY)
Dose (Gy)PWO_batch06lowdoselab27.qpcE. Auffray, EP_CMA
18/01/2000
LY
irr/L
Y0 (
%) LYloss=(LY0-LYirr)/LY0 (%)
Ioan DafineiRegional Centre ECAL-CMS Rome ITALY
Villa Olmo, Como 15-19 October 2001
Advanced Technology and Particle Physics
Pre-Production Crystal Properties
LY loss (%)
0
2
4
6
8
10
0 1 2 3 4 5 6 7 8 9 10
N = 32 Xtals StDev : 1.21% Mean : 3.39%
batch 1Front irrad., 1.5Gy, 0.15Gy/h
0
20
40
60
80
100
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 6.5 7 7.5 8 8.5 9 9.5 10
LY loss (%)
Statistics on 368 crystals Mean : 2.45 % StDev : 1.06%
Rej
ecte
d f
or
LT
slo
pe
< 1
.5%
/m
Rej
ecte
d f
or
LT
@35
0nm
< 1
0%
batch 8
0
4
8
12
16
20N = 33 Xtals
0 1 2 3 4 5 6 7 8 9 10LY loss (%)
StDev : 0.9% Mean : 1.92%
batch 14
N = 19 Xtals StDev : 1.21% Mean : 0.92%
0
4
8
12
16
20
0 1 2 3 4 5 6 7 8 9 10LY loss (%)
Ioan DafineiRegional Centre ECAL-CMS Rome ITALY
Villa Olmo, Como 15-19 October 2001
Advanced Technology and Particle Physics
Pre-Production Crystal Properties
Pre-Production in ChinaRadiation hardness characteristics
95
96
97
98
99
100
101
102
103
104
105
0 2 4 6 8 10 12
SIC800 (%LY)
SIC803 (%LY)
SIC807 (%LY)
SIC819 (%LY)
SIC829 (%LY)
SIC834 (%LY)
SIC840 (%LY)
SIC841 (%LY)
SIC849 (%LY)
SIC850 (%LY)
SIC858 (%LY)
SIC868 (%LY)
SIC869 (%LY)
SIC879 (%LY)
SIC880 (%LY)
SIC872(%LY)
SIC891 (%LY)
SIC883 (%LY)
SIC892 (%LY)
Dose (Gy)
Change of total light output during front irradiation at 0.15 Gy/h data for 21 crystals
LY
irr/L
Y0 (
%)
Ioan DafineiRegional Centre ECAL-CMS Rome ITALY
Villa Olmo, Como 15-19 October 2001
Advanced Technology and Particle Physics
Pre-Production Results
6000 Crystals produced by BTCP
0
10
20
30
40
50
set-98
dic-98
mar-99
giu-99
set-99
dic-99
mar-00
giu-00
set-00
dic-00
Dimensions Transmission
Light Yield Decay time
Slope/Rad.hardness
0
200
400
600
800
1000
set-98
dic-98
mar-99
giu-99
set-99
dic-99
mar-00
giu-00
set-00
dic-00
Planning Delivered
Increasedproduction rate
yieldImproved
stability of parameters
Xtals quality
Sept. 1998 to Dec. 2000
Ioan DafineiRegional Centre ECAL-CMS Rome ITALY
Villa Olmo, Como 15-19 October 2001
Advanced Technology and Particle Physics
To be produced before end 2004 :•56000 crystals for Barrel•16000 crystals for Endcaps
Present status :•6000 preproduction crystals•2000 production crystals
increased productivity is needed
New crystal development :Ingot diameter increase
Production Schedule
Started in 2001
Ioan DafineiRegional Centre ECAL-CMS Rome ITALY
Villa Olmo, Como 15-19 October 2001
Advanced Technology and Particle Physics
Recent Developments
1996
Barrel
32 mm
1999
Endcap
44 mm
End 2000
Barrel
65 mm
Crystal Growth Technology Steps
Ioan DafineiRegional Centre ECAL-CMS Rome ITALY
Villa Olmo, Como 15-19 October 2001
Advanced Technology and Particle Physics
Recent Developments
= 32 mm
= 65 mm
PWO crystals made in BTCP Bogoroditsk
Ioan DafineiRegional Centre ECAL-CMS Rome ITALY
Villa Olmo, Como 15-19 October 2001
Advanced Technology and Particle Physics
Recent Developments
Large PWO crystals made in BTCP Bogoroditsk
time (ns) %
30.0 80.3
50.0 89.9
100.0 96.4
300.0 99.3
1000.0 99.9
1525.5 99.9
A. N. Anenkov et all, Scint2001 Conference scintillation characteristics
Ioan DafineiRegional Centre ECAL-CMS Rome ITALY
Villa Olmo, Como 15-19 October 2001
Advanced Technology and Particle Physics
Recent Developments
A. N. Anenkov et all, Scint2001 Conference
saturation dose
radiation hardness
longitudinal uniformity
Large PWO crystals made in BTCP Bogoroditsk
Ioan DafineiRegional Centre ECAL-CMS Rome ITALY
Villa Olmo, Como 15-19 October 2001
Advanced Technology and Particle Physics
Recent Developments
radiation hardness
radial uniformitycenter side
A. N. Anenkov et all, Scint2001 Conference
Large PWO crystals made in BTCP Bogoroditsk
Ioan DafineiRegional Centre ECAL-CMS Rome ITALY
Villa Olmo, Como 15-19 October 2001
Advanced Technology and Particle Physics
Recent Developments
radiation hardness
Large PWO crystals made in BTCP Bogoroditsk
PWO 7365 1st irradiation at the Geneve Hospital
0
20
40
60
80
100
300 350 400 450 500 550 600 650 700
1i11irr1
Irr1 + 20'Irr1 + 40'Irr1 + 24h
Tra
nsm
issi
on (
%)
Wavelength (nm)
60Co
430 Gy
Ioan DafineiRegional Centre ECAL-CMS Rome ITALY
Villa Olmo, Como 15-19 October 2001
Advanced Technology and Particle Physics
30 35 40 45 50 55 60 65 70 75 80
LT@420
cou
nt
s
Transmission at 420nm (%)
N = 300Mean: 69.91%StDev : 0.85%
0
20
40
60
80
100
120
140
Batch P2 from CERN/ISTC production contract #1718
was used to compare:– 260 barrel crystals produced
with the standard technology
– 40 barrel crystals produced with the new technology
New vs Old Technology
LT@360
cou
nt
s
0
10
20
30
40
50
60
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70Transmission at 360nm (%)
N = 300Mean: 31.36%StDev : 3.3%
Ioan DafineiRegional Centre ECAL-CMS Rome ITALY
Villa Olmo, Como 15-19 October 2001
Advanced Technology and Particle Physics
260 barrel crystals produced with the standard technology
40 barrel crystals produced with the new technology
New vs Old Technology
0
20
40
60
80
100
120
140
0 1 2 3 4 5 6 7 8 9 10Slope@inflection (%/nm)
N = 300 crystals
Mean : 3.30%/nmStDev : 0.06%/nm
LT slope@inflection
cou
nts
0
50
100
150
200
250
300
5 6 7 8 9 10 11 12 13 14
N = 300 crystals
Mean : 9.1 pe/MeVStDev : 0.57 pe/MeV
LY@8X0
Light Yield (pe/MeV)
cou
nts
Ioan DafineiRegional Centre ECAL-CMS Rome ITALY
Villa Olmo, Como 15-19 October 2001
Advanced Technology and Particle Physics
New vs Old Technology
90
92
94
96
98
100
0 1 2 3 4 5
Low dose rate irradiation of some crystals from BatchP2-1
PWO_P7277 (%LY)PWO_P7356 (%LY)PWO_P7365 (%LY)PWO_P7366 (%LY)
Dose (Gy)PWO_batchP2lowdoselab27_1.qpc E. Auffray, EP_CMA10/06/2001
Front irrad., 1.5Gy, 0.15Gy/h
Ioan DafineiRegional Centre ECAL-CMS Rome ITALY
Villa Olmo, Como 15-19 October 2001
Advanced Technology and Particle Physics
• Success of the R&D phase– Increase of the production rate
– good quality crystals
– uniform optical properties
• Technology for ingots up to 65mm diameter is now well under control
• The possibility to further increase the as grown PWO diameter and to apply this approach to endcap crystals is realistic
• Present status of physics and technology of scintillating materials shows that the CMS Collaboration decision to use PWO crystals for the ECAL construction was the best possible choice
Conclusions
Ioan DafineiRegional Centre ECAL-CMS Rome ITALY
Villa Olmo, Como 15-19 October 2001
Advanced Technology and Particle Physics
Ready to Construct the CMS-ECAL
1st module of 400 crystals build in 2001 for ECAL
CERN Lab.27 EP-CMA
Casaccia
&
Conclusions