Transcript The ZEUS MVD - Istituto Nazionale di Fisica Nucleare

The ZEUS
Micro-Vertex Detector
Alessandro Polini
DESY
ZEUS MVD Group: Bonn Univ., DESY-Hamburg,
DESY-Zeuthen, Hamburg Univ., KEK-Japan,
NIKHEF, Oxford Univ., Padova, Torino, Bologna and
Firenze Univ. and INFN, UCL.
Villa Olmo, Como 15-19 October 2001
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Current(nA)
Outline
200
180
160
140
120
100
80
60
40
20
0
14C (bias 51V)
17C(bias 48V)
20C(bias51V)
23C(bias78V)
23C(bias65V)
30C(bias65V)
0
20
40
60
80
100
Voltage(V)
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Physics Motivation
Detector Design
Standalone Test Measurements
Read-Out, DAQ and Control Infrastructure
First Experience after Installation in ZEUS
Summary and Outlook
Villa Olmo, Como 15-19 October 2001
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A Microvertex for ZEUS at HERA
HERA:
ZEUS:
e± p collider
upgrade of tracking system:
2001 luminosity upgrade
•
MVD
•
Straw Tube Tracker
•
Global Tracking Trigger
•
Tagging of long-lived
particles (heavy flavour)
•
Reconstruction of
secondary vertices
L= 1.5
7.51031cm-2s-1
•higher sensitivity for very interesting,
low cross sections
•major changes in interaction region
•last bending magnet inside experiment
•higher backgrounds, risks of radiation
damage
Villa Olmo, Como 15-19 October 2001
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Detector Layout
Forward Section
410 mm
Barrel Section
622 mm
e±
p
The forward section consists of
4 wheels with 28 wedged
sensors/layer providing
r- information.
The Barrel section provides 3
layers of support frames (ladders)
which hold 5 full modules, 600 square
sensors in total, providing r- and r-z space points.
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Barrel MVD: Module and Ladder Structure
125 mm
Two single
sensors
are glued and
electrically
connected by
gold plated
Upilex foils
Two half modules
are then glued together
to form a full module
The Upilex
connection foils can
be bent and glued
to the ladder profile
Five full modules are
disposed over a
carbon fibre support
Villa Olmo, Como 15-19 October 2001
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Forward MVD Layout
Forward wheels:
• 112 Si planes with wedge shape (480 readout strips);
• r- measurement;
• 1 wheel made of 14x2 detectors;
• 4 wheels placed @ z = 311, 441, 571 and 721 mm from IP.
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Silicon Microstrip Detectors
•
120 mm
•
•
QRIGHT
QLEFT
p+ implantation of
the intermediate strip
Cc
Cint
Cc >> Cint > Cb
particle
The charge sharing is a non linear
function of the interstrip
coordinate x
Cb
20 mm
Interstrip coordinate x
Villa Olmo, Como 15-19 October 2001
•
n-doped silicon wafers (300 mm
thickness) with p+
implantations (12 or 14 mm
wide), HAMAMATSU PH. K.K.
512 (480 for forward sensors)
readout channels.
Using the capacitive charge
sharing, the analogue readout
of one strip every 6 allows a
good resolution (<20 mm)
despite the readout pitch of 120
mm.
Highest coupling to the front
end electronics if:
p+ implantation of
The readout strip
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Front-end and Read-out

Front-end Chip HELIX 3.0
– 128 channel analog pipelined programmable readout system specifically
developed for the HERA environment.
– ENC[e]  400 + 40*C[pF] (no radiation damage included).
– Data read-out and multiplexed over the analog out.
– Internal Test Pulse and Failsafe Token Ring (8 chips) capability.

Read-out
1 full module raw data
– 10 bit resolution ADC Modules with:

Common Mode, Pedestal and Noise Subtraction

Strip Clustering
 2 separate data buffers: cluster data (for trigger purposes) and raw/strip data for
accepted events.

Global Tracking Trigger
– Together with the Central Tracking Detector: new Global Tracking Trigger
System.
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Hit Reconstruction: from previous Test Beam Results
Intrinsic resolution of
a half module
Fast algorithm
with no assumption
on charge sharing
Large impact angles
require different
reconstruction
algorithms
Based on
charge sharing
parameterization
angle a (deg)
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The MVD System Test


Following the assembly up to the final MVD, extensive tests and monitoring
of the detector have been performed.
A Standalone Test Environment with a dedicated Cosmic Trigger has been
set up.
Aim:
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Final checks of modules, cabling, cooling
Laser alignment measurements
Setup a complete read-out scheme
Study detector response with real data
Monitoring of various system components:
Cooling, Temperature, Humidity, LV,
HV, Noise, Pedestals ,Dark Current.
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Large cosmic sample
acquired:
2.5 Million triggered
events.
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MVD Cosmic System Test

Landau distributions from different ladders:

C0L1 (0º)

C1L1 (50º)
S/N  13


The expected difference in the peak position is clearly seen!
Noise and Stability:
C1L1

Pedestal stable at the level of 1-2 ADC-counts

Entries above 20 ADC-counts in noise-distribution: 36 /25 (barrel/forward)

Channels with unstable noise-performance: 119 (total for barrel and forward)
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C0L1
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MVD Cosmic System Test Results
 ~80 mm
Without
any alignment
correction
First Track fit using all modules but one: resolution  ~80 mm
Dominated by systematics, confident to reach final resolution of  20 mm
Cyl. 0
Geometrical
efficiency
Cyl. 1
Cyl. 2
Faulty
Modules
(4 of 206)
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Detector I/V Observed Properties
During the system test increasing leakage currents have been observed
in some modules.
Further studies have shown that at decreasing temperature the relative
humidity rises and the breakdown voltage decreases
21.8° 62%h.
200
180
Increasing temperature
160
Current(nA)
140
120
14C (bias 51V)
100
17C(bias 48V)
80
20C(bias51V)
60
23C(bias78V)
40
23C(bias65V)
20
30C(bias65V)
0
0
20
40
60
80
100
Voltage(V)
A careful checking and control of the humidity
is required for the ZEUS MVD!
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22.5° 31%h.
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MVD Commissioning in ZEUS

ZEUS Requirements

DAQ System and Global Tracking Trigger

Radiation Monitor

First (Cosmic) ZEUS data
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The ZEUS Detector
e±
27.5
GeV
CTD
FLT
GFLT Accept/Reject
Other
CAL
Components CTD
SLT
SLT
Global Second
Level Trigger
5ms pipeline
5ms pipeline
920
GeV
Other
Components
Global First
Level Trigger
Event Buffers
p
CAL
FLT
107 Hz
CTD
Front End
~0.7 ms
500Hz
Event Buffers
CAL
Front End
~10 ms
GSLT Accept/Reject
40Hz
CAL
CTD
Event Builder
Third Level Trigger
bunch crossing time: 96 ns
cpu
ZEUS: 3-Level Trigger System
(Rate 500Hz405 Hz)
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cpu
cpu
cpu
cpu
cpu
5Hz
Offline Tape
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The MVD Data Acquisition System and GTT
Central Tracking Detector Read-out
Analog Data
MVD HELIX Front-End & Patch-Boxes
MVD VME Readout
NIM + AnalogLinks
Latency
Lynx
OS
CPU
HELIX
Driver Front-end
Lynx
OS
CPU
VME HELIX Driver Crate
Clock +
Control
ADCM
modules
VME (C+C Slave)
Crate 2 (MVD forward)
NIM + AnalogLinks
Latency
Lynx
OS
CPU
ADCM
modules
Clock+
Control
NIM + AnalogLinks
Latency
Lynx
OS
CPU
VME (C+C Slave)
Crate 1 (MVD bottom)
ADCM
modules
Clock+
Control
Global First Level
Trigger,Busy, Error
NIM +
Latency
Lynx
OS
CPU
VME (C+C Master)
Crate 0 (MVD top)
CTD 2TP
modules
VME TP connection
Data from CTD
NIM +
Latency
Lynx
OS
CPU
GSLT 2TP
modules
Global Tracking Trigger Processors (GFLT rate 800 Hz)
TP connection to
Global Second Level
Trigger
Fast Ethernet/
Gigabit Network
Run Control and Online
Monitoring Environment
Global Second Level
Trigger Decision
NIM +
Latency
Lynx
OS
CPU
Slow control +
Latency Clock modules
VME CPU Boot Server
and Control
Network Connection to
the ZEUS Event Builder
Villa Olmo, Como
15-19
(~100
Hz)October 2001
Main MVDDAQ server, Local
Control, Event-Builder Interface
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The Global Tracking Trigger
Concept:
 Combined second level trigger using information from CTD, MVD
(and the new Forward Tracker)
 Higher quality event reconstruction and rate reduction
 Z vertex resolution 9 cm (CTD only)  400 mm (MVD+CTD+GTT)

Decision required within existing SLT (<15 ms)
Read-out Latency
After GTT processing
MVD-GTT Trigger Latency
Dijet sample
ms
Input rate 400Hz
Full online latency measurements and data file playback capability.
First average latencies obtained using MonteCarlo events through
complete DAQ system and trigger algorithm are encouraging.
Villa Olmo, Como 15-19 October 2001
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The ZEUS Radiation Monitor System
•16 PIN diodes in 8 modules ( 1cm2, zfwd=110, zrear=-100 cm)
• continuous radiation measurement, beam dump
•8 RADFET (zfwd=200, zrear=-160 cm)
• real-time integrating dosimeter:
• wide dynamic range 1 mGy to 3kGy
•Thermo-luminescence dosimeters (TLD):
• two types (neutron, photon sensitive)
• measure precisely integrated dose (monthly exchanged)
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Radiation Monitoring
During machine setup
Proton beam current
In HERA
PIN diode current
Increase of
plateau current
•~50 Gy absorbed so far (diode measurements,
confirmed by Radfets & TLDs)
•Final diode readout with beam dump capability
being finalized (automatic beam dump at
integrated dose of 10..50 mGy per accident).
•Expected background irradiation in 5 years of
operation (experiment lifetime): 50 Gy/year = 5 µGy/s
•MVD and readout electronics tested up to 3 kGy,
operation still possible, but reduction of S/N
•Max. tolerable dose: 100-300 Gy/year = 10-30 µGy/s
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MVD Leakage Current
increased ~1mA
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ZEUS Cosmic Data with CTD and MVD
Before HERA commissioning started (July 2001), there was a short
time window for a cosmic data run with the full ZEUS detector.
A Cosmic Event based on a CTD and Calorimeter Trigger.
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Summary and Outlook

System Test
– Complete MVD-system has been tested continuously for a longer period.
– Stable operation of: Slow Control, Cooling, LV and HV Systems.
– Dark currents are fairly stable in time at depl. voltage ( dry air flow is
important!)
– Pedestal and noise performance is good. Faulty modules <2%.
– Cosmic results show expected performance (Landau distributions, etc.).

Installation and Commissioning in ZEUS
– MVD installation was successful (detector integration, cable routing).
– Functioning of the DAQ System, the GTT environment as well as the Control
infrastructure established.
– Radiation monitoring (active and passive system) available and working during
HERA startup.
– Encouraging results looking at the next high luminosity period.
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