ALICE ZDC STATUS REPORT

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ALICE ZDC STATUS REPORT

• Responsabilities shared by
• Universita del Piemonte Orientale, Alessandria,
  Italy
• INFN-Cagliari and Universita di Cagliari, Italy
• INFN-Torino and Dipartimento di Fisica
  Sperimentale, Universita di Torino, Italy

• Outline
• Activities in the year 2006
• Beam test of the second proton calorimeter
  (ZP2)
• Construction of the support platforms
• Design of the non-commercial readout and
  trigger modules
• Planning for the year 2007
• Integration of the calorimeters on the platforms
• Commissioning of the platform on surface
• Installation of the calorimeters in the tunnel
• Construction of the trigger custom VME module
• Commissioning of the readout system

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ZDCs for the ALICE experiment

• The ZDC detector is made by two sets of
  calorimeters, located at opposite sides w.r.t.
  IP2, 116 meters away from it. Each set of
  detectors consists of
• 2 hadronic calorimeters
• 1 for spectator neutrons (ZN)
• 1 for spectator protons (ZP)
• 2 forward EM calorimeters
• at 7 m from IP2, on RB24 side
• covering 4.8 lt h lt 5.7

ZP
ZN

• Used during HI runs to measure
• centrality of the collision
• absolute luminosity
• ZP may be used during pp runs to study
  diffractive physics

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Status of the construction

• All the four hadronic calorimeters (ZN1, ZN2,
  ZP1, ZP2) already assembled and ready to be
  mounted on the final movable platform
• ZP2 tested on beam at SPS in 2006
• One of the two ZEM assembled, final mechanical
  support not yet finalized
• The custom electronic modules for the trigger are
  in construction
• The support platform is assembled and
  commissioning is under way
• The long signal cables from the tunnel to the CR4
  counting room are being pulled in the frame of
  LHC cables campaign

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ZP2 test at SPS

• ZP2 was tested at H6 beam line in summer 2006
• Due to various accelerator problems during the
  allocated period we could use only
• positive hadron beam with E 120 GeV
• Aim of the test
• Equalization of the four towers
• Measure uniformity of the response of the
  calorimeter as a function of beam impact point on
  its front face
• Check the resolution

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ZP2 test results
Response of the four towers after online
equalization as a function of the beam impact
point on the front face of ZP2
Energy resolution ? 25.5/-0.4 same as ZP1
resolution (25)
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The e.m. calorimeter (ZEM)

• Dimensions 7x7x20.6 cm3
• Passive material 4O lead absorber slabs, 
• each of
  them 3 mm thick
• tilted
  at 450 w.r.t the LHC axis
• Active material quartz fibers
• arranged in
  ribbon
• between the absorber slabs
  
• Air guide to collect the light from the fibers
• up to a photomultiplier.

• One of the two ZEM is assembled
• The second is ready to be assembled
• Final mechanical support and integration
• is currently being defined

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ZDC trigger readout

• Analogic signals digitized with commercial QDC
  VME (CAEN V965)
• Trigger L0,L1,L2 received by a modified Dimuon
  Trigger Readout Card (DARC)
• Data sent to DAQ through the same DARC card
• VME CPU used to read QDCs and to send data to
  DARC, since the DARC card is a slave module
• ZDC provides 3 centrality triggers and the e.m.
  dissociation trigger at L1 level a custom card
  used to send the triggers to CTP

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ZDC trigger and readout layout
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ZDC trigger

• e.m. dissociation trigger (L0) for some special
  runs
• analog signal from ZN PMTc on RD26 side (2nd
  anode output) send to trigger rack C23 and
  discriminated to select one spectator neutron
• Very fast cable is pulled
• LATENCY TOO LONG ( gt 900 ns)
• Centrality trigger (L1) and e.m. dissociation
  trigger (L1)
• 3 centrality triggers ZDC_peripheral,
  ZDC_SemiCentral, ZDC_Central
• mutual e.m. dissociation (1 spectator
  neutron on both side of IP) ZDC_Special
• All commercial modules provided
  (fan-in/fan-out,discriminators,logic units)
• Custom module in preparation
• Conversion from ECL to LVDS and toggling signal
  for timing to meet
• the Central Trigger Processor requirements

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ZDC readout (2)

• The readout is based on a modified DARC board
• The DARC is a VME slave card developed by
  Subatech-Nantes for the DAQ of the Dimuon Trigger
  and has a FPGA which implements all the logic
  required to receive the triggers from the CTP and
  to communicate to the DAQ via the SIU.
• For the ZDC application one of the FPGA in the
  DARC card will be modified.
• The ZDC DARC card is available at the Cagliari
  electronic lab.
• The work on adaptation is ongoing

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DCS calibrations

• DCS used to
• control HV to PMTs (CAEN SY1527)
• control vertical positioning of calorimeters
• 
  Work in progress
• Calibration tasks required using ECS
• Pedestal runs
• Fibre transparency monitoring and PMT gain
  stability by means of laser light injection
• Absolute PMT gain measurement with single
  photoelectron peak from cosmic rays
• logic modules ready
• required software in preparation

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ZDC support platform

• Assembly of the support platform completed
• Few issues solved
• 15 cm more space required to fit PMT monitoring
  system
• ECR done and accepted
• The jacks were sent by the industry with a non
  radhard grease
• the grease had to be replaced
• Each calorimeter is lifted by two jacks, but the
  movement is not synchronized
• A mechanical piece had to be designed and
  manufactured
• Commissioning of the platform movement is under
  way at Point2

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ALICE ZDC Planning
ZDC activities up to the day one
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ZDC Commissioning

• Commissioning of the support platforms on surface
• under way
• Cable connection to detector , check HV, check
  signals from PMTs
• 1 June 2007 -15 June 2007
• Installation of the readout and trigger
  electronics in CR4
• 1 June 2007 31 July
  2007
• Readout Commissioning
• 1 July 2007 30
  September 2007

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Summary

• ZP2 has been tested in July 2006
• Construction of ZEM started, not yet completed
• The support platform assembled
• Commissioning of the platforms under way
• Cables from tunnel to CR4 pulled
• Custom electronics for trigger in construction
• VME readout card modified but not yet tested

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Backup slides
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ZDC on the support platform
ZN and ZP at garage position
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ZP for ALICE detector description
Passive material brass ? 9.0 g/cm3 30
grooved slabs, each of them 4 mm thick,
Dimensions 22.8x12x150 cm3.
Active material quartz fibers pure silica
core, fluorinated silica cladding and a hard
polymer coat with a diameter of 550, 600, 630 mm
respectively. The numerical aperture is 0.22.
1680 quartz fibers embedded in the absorber with
a pitch of 4 mm. Fibers placed at 0? with
respect to the LHC axis Light come out from the
rear face of the calorimeter.
One out of two fiber is sent to a photomultiplier
(PMTc), while the remaining fibers are collected
in bundles and sent to four different
photomultipliers (PMT1 to PMT4), forming four
independent towers. The chosen PMT is the
Hamamatsu R329-02, with quantum efficiency around
25.

• rough detection of the beam position

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ZDC platform requirements

• ZP and ZN can be vertically moved independently
• ZN normally at garage position (20 cm lower
  than beam plane)
• during p-p runs
• ZP may be used in p-p runs to select
  diffractive events
• The precision on the ZDC positioning is
  required to be 250 mm
• value comparable with the error in the
  reconstruction of
• the centroid of the spectator neutrons

• Interference with the LHC
• vacuum chamber
• - 3 mm clearance between
• beam pipes and calorimeters
• - anti-collision switches

ZN
ZP
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ZDC readout (1)
CR4-X04
CR4-X04
ADC CAEN V965 already procured
ZDCRC Custom VME slave module
Analog Inputs (25 ch)
VME Output Buffer 32 events deep
through CPU
SIU
TTCrx
L0 from CTP
clear
gate
busy
optical fiber L1,L2 from CTP
from ZDC
to CTP
to LDC

• ZDCRC readout controller to receive L0,L1,L2
  trigger and to send data to DAQ
• VME card is a special version of the
  Dimuon-trigger Alice Readout Controller (DARC)

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ZDCs for the ALICE experiment
The ZDC detector is made by two sets of
calorimeters, located at opposite sides with
respect to the Interaction Point (I.P.2), 116
meters away from it, where the two LHC beams
circulate in two different pipes. Each set of
detectors consists of 2 hadronic spaghetti
calorimeters, 1 for spectator neutrons (ZN),
placed at 0 with respect to LHC axis, and 1 for
spectator protons (ZP), positioned externally to
the outgoing beam pipe. The ZDC detector is
completed by 2 forward EM calorimeters placed at
about 7 m from I.P.2, on RB24 side, covering the
pseudorapidity range 4.8 lt h lt 5.7.
VACUUM CHAMBER
D1 DIPOLE SEPARATOR
QUADRUPOLES
EM ZDC
NEUTRON ZDC
PROTON ZDC
INTERACTION POINT
not in scale
116 m
7 m