GERDA: Status Review
C.M. Cattadori- INFN-Milano Bicocca
Per la collaborazione GERDA
Outline
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The GERmanium Detector Array for 0nbb decay searches
project
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Status of the GERDA setup.
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The main milestones
The design
The Water Tank & The Cerenkov Muon veto
The Cryostat & cryogenic system
The Ge detectors
The Ge detectors readout
The calibration system
Next steps
Preparation of GERDA Phase II
Conclusions
Criticita’
Richieste finanziarie
Roma, 31 May 2010
C.M. Cattadori - CSNII
clean room – rdy
status
The rendering of the setup
status:
phase I lock – under test
cryo-mu-lab
Insert rendering as at KTK public lecture slide
n.27
μ veto
phase I array
rdy (scaled:)
rdy
FE electronics
2 version avlb
control room
water plant
Rn monitor
cryostat - rdy
water tank - rdy
Roma, 31 May 2010
GERDA bldg - rdy
C.M. Cattadori - CSNII
LAr fill : Oct/Nov 09
GERDA: a novel approach to the background issues
GERDA goal: build a setup with a B< 10-3 [c/kky] @ Qbb
GERDA distinctive features to reduce bckrgd of 10-6
• Ge diodes operated naked in LAr
• Ge diodes with enhanced PSD features
Roma, 31 May 2010
C.M. Cattadori - CSNII
GERDA milestones
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Proposed in 2004 & funded by MPG
Approved in 2005 by LNGS with location in Hall A
2005 Funded by BMBF, INFN, DFG (R&D), and Russia in kind
WT & related plants:
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Cryostat & cryogenic systems
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Constructed in 2008
Clean room & Lock
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Contract signed in 2007
Construction @ company site in 2007-2008
Delivered @ LNGS in 2008
filled with LAr in Dec ’09 & cryogenic commissioning completed
Building
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Contract signed in 2006
Construction in LNGS Hall A 2007-2008
Muon veto constructed in 2009
Constructed in 2009> Lock tested in 2009, moved underground in
2010
Detectors:
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Refurbishment technology defined in 2008 after proofing long
term
stability
Roma,
31 May
2010 in LAr
C.M. Cattadori - CSNII
Pictures from the construction time (2007-2010)
Roma, 31 May 2010
C.M. Cattadori - CSNII
Pictures from the construction time (2007-2010)
Roma, 31 May 2010
C.M. Cattadori - CSNII
The Cerenkov muon veto: Status
•77 PMTs
•PMTs tested in water during
the last water filling/emptying
test (april 2010): seen the firsts
m.
• All PMTs working apart 1 on
the floor (cable problem)
• DAQ is working: its tests and
debugging ongoing
• The test capsule kept 4 years
in water at Tubingen, when
open is OK.
Roma, 31 May 2010
C.M. Cattadori - CSNII
The Cryostat: design
Build with st.st.
< 5 mBq/kg
The Rn
shroud
The cooling serpentine: to sub-cool
the LAr
• dedicated meas show that Rn in
cryostat
~55 mBq with manifold, bellow, piping,
sensors, cabling, ….
• Temp. difference suppresses exchange
of LAr from neck and tank
• Rn in convective layers w/o shroud:
30 mBq => 2·10-3 cts/(keV·kg·y)
• Rn in convective layers with shroud:
30 mBq => 1.5·10-4 cts/(keV·kg·y)
Roma, 31 May 2010
• Homogenous mixing of radon in LAr:
C.M. Cattadori
30- CSNII
mBq => 4·10-4 cts/(keV·kg·y)
The Cryostat: Status
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cryostat has been cooled (7 t LAr) & then
filled (0.7 m3/h) in nov/dec 2009, taking LAr
from GERDA storage dewar, through the
GERDA cryogenic lines. WT was empty.
No problems during filling, and then keeping it
cold
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Evaporate rate as expected
Active cooling switched on in Jan-10:
works as expected, zeroing the LAr
evaporate rate.
Cryostat & Cryosystem PLC controlled:
they are remotely visible & controllable
via Web interface
Several tests on PLC performed: OK
Cryostat Critical parameters replied to
LNGS safety control room.
Roma, 31 May 2010
C.M. Cattadori - CSNII
The WT, water related plants (INFN)
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The WT effective volume is ~ 600 m3.
Water supplied from demi-Borexino
plant through a dedicated pipeline
Water filling (~1 m3/h) tested several
times (2m, 4m, 8.4 m height).
The safety procedures require that in
case critical parameters (P in cryostat &
in the gap between internal & external
cryo-vessels) above thrs release the
water < 2h
Water will be drained at ~100 l/s
through:
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Roma, 31 May 2010
A dedicated fast drain water line
(recently reconfigured and tested) at
flow rate of ~ 60 l/s (tested 19th april).
Flow rate kept constant by butterfly
valve PLC controlled
One pipeline towards GNO pits (17 l/s)
+ 1 pipeline from exhaust heater
 may 2010: proved the complete
emptying of the WT
< 2h.
C.M. Cattadori - CSNII
The Lock, Detector handling & suspension
systems(MPP-MU & MPIK-Hd)
• The lock(vacuum env., linear pulley & suspension system), the
glove box for detector handling, and the PLC (move up/down,
shutter control etc.) are installed in clean room and in final test
• The 1st string cabling (6 subminiature Teflon, 50 Ohm coax
cables for signal & LV (10 mBq/m) and Teflon HV cables: has
been tested: OK
• The 3 string c-lock is being assembled: 3 strings (3 detectors
each) suspended and moved by one linear pulley/chain. It will be
Roma, 31
May 2010
moved into
clean
room in ~ 2 months C.M. Cattadori - CSNII
The Phase I enrGe detectors (Russia &
MPIK-Hd)
• 8 enrGe (former HdM&IGEX) + 6 natGe
(from GTF) p-type coaxial Ge detector
available
• mass:1-3 kg
• Cdet = 30-40 pF
• Deployed in strings of 3 detectors each
• Mounted in low-mass Cu holders
• HV contact: on Li surface by pressure
• Readout contact: in borehole springloaded
• All the detectors have been tested naked
in LAr and perform well (I-V & R < 3 keV
@ 1.332 MeV).
• Long term stability experimentally proved
Roma, 31 May 2010
C.M. Cattadori - CSNII
The Ge detector readout: Front-end (INFN)
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2 cryogenic FE circuits available similar
architecture: external JFET + following
amp. stage (ASIC or CMOS OPAMP)
LAr
FADC
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Adopted in LAr measurements with coax
(Phase I) and BEGe detectors.
Achieved Performances @ LN :
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ASIC single-ended preamplifier
produced in 0.8mm 5V CZX CMOS
technology
Intrinsic noise < 1 keV (< 150 e r.m.s.)
Rise time: 30-40 ns
Radiopurity (232Th) with screened components:
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350 mBq/PCB (3ch)for ASIC FE
Roma, 31 May 2010
C.M. Cattadori - CSNII
150 mBq/PCB (3ch) for CC2 (based on commercial
CMOS OPAMP)
CC2 circuit based on
CMOS OPAMP
The Phase I Ge detector readout DAQ (INFN)
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Ge signal is digitized by FADCs (14 bit, 100 MHz,
custom design and production) installed in water
cooled cabinet. T monitor implemented.
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Internal thrs independent on each ch., filtered,
FPGA set & control
Data transfer based on FPGA
It can manage 2kHz/ch ev rate transferring data
at 132 MB/s
The DAQ software waveform display & GUI &
software to reconstruct the energy installed and
running.
Tested with BEGe detector
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R= 1.6 keV@60Co
Thrs: ~ 10 keV
Dyn. Range: 6.6 MeV
Roma, 31 May 2010
C.M. Cattadori - CSNII
FADC
HV + NIM
The Ge detectors performances achieved so far in LAr
in summer 2009 tests (first commissioning)
Modifications to the detector suspension and moving (up/down) defined and
implemented
autumn/winter
Clean glove in
box
(N2/hepa) 2009-2010
with commissioning lock
2.9 keV (FWHM) @ 1.3 MeV
Best resolution achieved in setup:
2.7 keV (FWHM)
Roma, 31 May 2010
C.M. Cattadori - CSNII
The Calibration System
(Zurich & INFN-LNGS & INFN-MiB)
 Several
232Th
sources available
commercial & custom made
 25.5 kBq commercial available
 ~ 14 kBq custom (PSI) under meas
at Geel
 30 kBq custom (PSI) (in production)
 40 kBq custom (Mainz) (in
production)
providing an event rate in detectors of ~
600 Hz in calibration allowing calibration
~1h
 Ta ring: to shield detectors when sources
are in parking position
 parasitic n-activity of sources from (a,n)
reaction on substrate materials measured
with dedicated setup
Roma, 31 May 2010
C.M. Cattadori - CSNII
(2.7 ± 0.5) x 10-2 n/s for the 14 kBq source
Source string
position
The Next steps
In the next months we will follow this general scheme :
 Test with mockup & capacitors of the 1-string arm
(ongoing). Last week problem on HV lines
 Optimization of noise in the underground setup
(grounding, tests with FE+ capacitors and detector
mockup). At present noise is at level of 2.3 keV on
pulser line
 Test run with 2 natGe GTF coaxial detectors for a
couple of months to measure achieved background
 Install 3-string lock
 Test it with mockup & capacitors
 Deploy the enrGe detectors
Roma, 31 May 2010
C.M. Cattadori - CSNII
The preparation of GERDA Phase II: enrGe purification
email circulated on 30 April 2010
Dear Colleagues,
This afternoon the zone refinement of the enriched germanium was finished.
35.5 kg >50 Ohm material was produced.
94% of the theoretical germanium quantity is now 6N
material.
With the last tail (1.1 kg) in total we have 36,6 kg metal, 97% of
the 37.5 kg
The integrated exposure is about 5.2 days including the
transport from Geel.
All the material is packed in two boxes and is underground in the
Rammelsberg mine.
Sincerely,
J.Janicsko
_______________________________________________
Gerda-list site list
[email protected]
https://www.mpi-hd.mpg.de/mailman/listinfo/gerda-list
Roma, 31 May 2010
C.M. Cattadori - CSNII
PHASE II: Crystal Pulling R&D
GERDA is pursuing with IKZ
(Berlin) an R&D program
on Ge cystal pulling that is
strategical for GERDA &
for Ge community.
 Crystal pulling at IKZ and
Canberra confirm that
ECP material & PPM
processing suitable for
HP-Ge production
 IKZ grew 21 Czochralski
crystals in total
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Best net-impurity level
reached 6 1010 cm-3 (ptype) from the seed end of
crystal
21
Roma, 31 May 2010
R&D program on p-type crystal pulling,
from deplGe, ongoing @ Canberra
(USA & Olen) since spring 2009.
GERDA provides deplGe
4 crystal pulled quality grade for
detector production in 2009
~70 mm
C.M. Cattadori - CSNII
PHASE II Detectors allowing enhanced PSD:
Segmented or BEGe
P-type thick window BEGe
detector (80 x 40 mm)
0nbb-like
g-bgd
18-fold n-type segmented
detector
•Applying PSA cuts and requiring 90% survival
probability for the 232Th DEP (mostly Single Site
Events 0nbb-like)
• 12% survival of the g-line 212Bi line (mostly MultiSite Events g-bgd like)
DEP
89.2% ±0.9%
10.1%0.7%
Roma, 31 May 2010
• Segmented & BEGe show similar PSD
performances, but BEGe simplest readout and
cabling  benefit for setup radiopurity
• 3 natGe + 2deplGe BEGe detctors tested so far: all of
Cattadori - CSNII
themC.M.
excellent
En Res < 2.0 keV @ 1.332 MeV
PSD: comparison of results from all the BEGe tested in GERDA
PSD Acceptance [%]
Dim.sns
Conta
ct dim
[mm]
Mass
[g]
Vdepl
[V]
Compton
@Qbb
DEP
1592
keV
FEP
1621
keV
SEP
2103
keV
FEP
2614
keV
81 x 32
Hd
15
868
4000
3700
39 ± 2
90±1.6
9.5±1.5
5.8 ±
0.6
7.7 ±
0.7
70 x 32
LNGS
15
632
3000
2600
37.5±0.5
90±0.6
11.5±0.1
6.2±0.4
6.4±0.1
60 x 26
Geel
15
390
3000
45 ± 2
90 ± 3
18 ± 3
6.8 ±1.7 14 ± 3
80 x 30
Geel
15
825
3500
49 ± 2
90 ± 3
29 ± 2
23 ± 2
74 x 33
Depl CC
9
752
3500
38.3 ± 0.3
90 ±1.1 10 ± 0.6
5.4 ±0.3 8.3 ±
0.1
74 x 32
Depl DD
22
~750
3500
39.8±0.3
90±1.1
5.8±0.4
Roma, 31 May 2010
C.M. Cattadori - CSNII
11.3±0.6
Not
avlbl
8.8±0.1
Phase II: The recentest results with bare BEGe (80 x 40 mm) &
cold FE in LARGE setup (@GDL):
LAr scintillation light
readout implemented
BEGe detector
Roma, 31 May 2010
C.M. Cattadori - CSNII
228Th
source: LArveto & PSD bckgrd rejection power
Detector: 80x 30 mm BEGe + cryogenic FE
Roma, 31 May 2010
C.M. Cattadori - CSNII
Conclusions
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Thanks to GERDA collab efforts and LNGS technical staff, the
setup has been completed and is at present in commissioning.
Cryostat is filled, WT has been filled and drain of water < 2 h has
been proved.
Recommendations of safety review have been implemented
GERDA collaboration is doing all the efforts for final integration,
debugging and then startup (in these days problem with HV lines)
Delicate moment, necessary to proceed carefully
First technical run with natGe detector is approaching to first
measure the background rate
Run with enrGe will then follows (time schedule depends on the
outcome of test runs)
GERDA Phase II is in preparation: very good results with BEGe,
The collab. will decide about Phase II detector type in summer
2010.
Roma, 31 May 2010
C.M. Cattadori - CSNII
Criticita’: Risorse umane
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Necessari per la sopravvivenza dell’attivita’
Manca candidato
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Criticita’ segnalate a Presidente CSNII, Referees, Direttori
LNGS e MiB.
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1 articolo 23 per LNGS per 1 fisico (dott. Assunta di Vacri con
R5)
1 AdR o contratto tecnologico per laureato fisico/ingegnere
elettronico a LNGS o MiB
1 AdR o Contratto tecnologico per laureato fisico/ingegnere a
MiB
1 fisico (Dottorando?) a MiB per analisi dati
A LNGS buon supporto tecnico
A MiB supporto tecnico quasi nullo
Scollamento gruppi GERDA da Universita’ rende minimo (a
LNGS) e nullo (a MiB) flusso di laureandi e dottorandi
Collaborazione gruppi Universitari AQ e MiB (docenti attivi in
attivita’ INFN) inadeguata.
Roma, 31 May 2010
C.M. Cattadori - CSNII
Richieste finanziarie per Data Storage @ LNGS
0.5 TB

Oggetto di questa richiesta
21 Disks
2TB each
RAID6 36 TB
Prezzo : 550-650 Euro/disco
secondo sconto.
Interpellata ditta che ha vinto l’ultima
gara di storage ai LNGS.
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N.2 server Fujitsu CONSIP
(uno backup dell’altro)
N.1 server per data analysis and
preprocessed data management
@ MiB
Roma, 31 May 2010
C.M. Cattadori - CSNII
GERDA
Richieste finanziarie
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1 modulo HV CAEN 4 ch per germani per bias
detectors Large (3.)
7 kEuro per
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rifacimento flange HV (UHV e sigillate) + nuovi cavi
(16 ch) (consumo)
Acquisto FET Moxtek, AD etc a Cin=1,2 pF
Roma, 31 May 2010
C.M. Cattadori - CSNII
EXTRA SLIDES
Roma, 31 May 2010
C.M. Cattadori - CSNII
Why 76Ge is an experimentally appealing 0nbb
candidate?
 Germanium detectors are an established technology: 76Ge is the
pioneering isotope (‘60 ) of the searches for 0nbb.
 Feasible to scale up experiment by subsequently adding more
detectors GERDA staged approach (Phase I +Phase II)
 Ge density = 5.3 g cm-3  compact setup
 Source = detector  high efficiency!
 High intrinsic purity and energy resolution O(0.1%-0.2%) allowing
understanding of background sources and geometry.
0.89 > 0.9
Sensitivity
on T1/20n
110 kgy Phase II
76

20 kgy Phase I
76Ge
< 4 keV
0.001-0.01 c/kky
isotopic abundance = 7.44 %, but enrichment of 76Ge possible at
centrifuge up to >80% (reasonable cost)
 Low Atomic Weight (1 kg of 76Ge = 13.1 Moles = 7.9 x 1024 nuclei)
Roma, 31 May 2010
C.M. Cattadori - CSNII
Why an experiment on 76Ge 0nbb
decay?
214Bi
 A debated claim @ 4.2 s indicate
evidence of 0nbb with
T1/2 = 1.2 x 1025 y
mee= 440 meV with KK NME
 Estimated NME favorable in all the
models T1/20n ~ 1027 y (for <mn>= 40
meV: M0nnucl ~ 4
 Qbb=2039.06±0.05 keV
(T1/20n)-1 ~ 5 x 10-17 [y-1] F0n (Q,Z) |M0n|2 mn2/ me2
0nbb half-life
Measured qty
Roma, 31 May 2010
Scale factor
Phase
space…
Nuclear
Effective Majorana
Matrix C.M. Cattadori
neutrino
mass
- CSNII
Elements
Deduced qty
?
0nb
b
214Bi
GERDA: Sensitivity
0n
1/ 2
T
Assumed E resolution: E = 4 keV
4.16 10 26 y a

ns
W
Mt
BR
From Vissani, Strumia hep-ph/0606054v2
KK claim
270 meV
110 meV
GERDA I, II
phase II
+20kg enrGe
phase I
18kg enrGe
KKDC
claim
GERDA I scrutinize in ~ 1 year data taking (assuming 18 kg y exposure) the KK
claim: if true bb decay GERDA will have 7 cts, above bckg of 0.5 cts  probability
that bckg
simulate signal ~ 10-5
Roma, 31 May 2010
C.M. Cattadori - CSNII
GERDA: The Collaboration
Location:
http://www.mpi-hd.mpg.de/GERDA
Roma, 31 May 2010
~ 95 physicists
17 institutions
6 countries
(Germany, Italy, Russia,
C.M. Cattadori - CSNII
Poland,Belgium,Switzerland)