ALICE ZDC STATUS REPORT

1
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

• Summary
• Activities in the year 2004
• Construction of the first proton Zero Degree
  Calorimeter (ZP1)
• Test at the CERN SPS with hadron and electron
  beams
• Test results
• Planning for the year 2005
• Construction of the second proton Zero Degree
  Calorimeter (ZP2)
• Start executive project of the support platform

2
ZDCs for the ALICE experiment

• The ZDC detector is made by two sets of
  calorimeters, placed on bothsides of the
  I.P.,each one composed by
• 2 hadronic spaghetti calorimeters, 1 for
  spectator neutrons (ZN) and 1 for spectator
  protons (ZP), placed at 0 with respect to LHC
  axis, at about 116 m from the Interaction point
  where the beam pipes are separated.
• a forward EM calorimeter placed at about 7 m from
  I.P., 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
DIPOLE CORRECTOR
XY2001
7 m
116 m
3
STATUS of CONSTRUCTION

• ZN1 and ZN2 already assembled and tested
• Ready to be mounted on the movable platform
• ZP1 assembled and tested
• Ready to be mounted on the movable platform
• ZP2 to be assembled in the summer
• ZEM to be assembled at the end of the year
• User requirement for the design of the platform
  defined design and construction is under the
  responsibility of CERN
• Most of the electronics for trigger and readout
  already procured (commercial modules)

4
ZP for ALICE detector description
Passive material brass ? 9.0 g/cm3 30
grooved slabs, each of them 4 mm thick, stacked
to form a parallelepiped 22.8x12x150 cm3.
Active material quartz fibers pure silica
core, silica fluorinated cladding, and a
hard polymer coat with a diameter of 550, 600,
630 mm respectively. The numerical aperture is
0.22.
The active part of the detector is made of 1680
quartz fibers embedded in the absorber with a
pitch of 4 mm. The fibers are placed at 0? with
respect to the initial particle direction and
come out from the rear face of the calorimeter.
One every two fibers are sent to a single
photodetector (PMTc), while the remaining fibers
are connected to four different photodetectors
(PMT1 to PMT4), collecting the light from four
towers. The chosen PMT is the Hamamatsu R329-02,
with quantum efficiency around 25.

• rough detection of the beam position

5
ZP1 assembly (july 2004)
brass grooved plates
quartz fibers
segmentation
ready to be tested
6
Beam test at SPS experimental set-up

• ZP1 was tested at H6 beam line in summer 2004
  with
• hadron beam ( E 50 200 GeV )
• electron beam ( E 50 180 GeV )

- S1, S2, S3, S4 plastic scintillators to
provide trigger - MWPC multiwire proportional
chamber to define impact point on
the calorimeter front face - MU1, MU2 plastic
scintillators to detect muons
7
ZP1 beam test results pions and electrons
ZP1 response to 120 GeV pion beam
ZP1 response to 120 GeV electron beam
Fit to data
where
8
ZP1 beam test results linearity
ZP1 response shows a linear behavior as a
function of p- and e- beam energy in the range
from 50 to 200 GeV.

• ZP1 is highly not compensating
• but in ALICE
• ZP measures the number of spectator protons,
  which have the same fixed energy as the beam
  nucleons.
• Charged particle produced at IP are bent by D1
  separator magnet outside ZP.

9
ZP1 beam test results energy resolution
The black solid lines are the results of the
fit
Extrapolation to the ALICE proton spectator
energy (2.7TeV)
Fulfills the ALICE requirements (TDR)
10
ZP1 test results uniformity

• Sampling frequency adequate for hadrons

• Visible transverse shower
• dimensions 14 mm

(Light from PMTc)/(Total light) vs xbeam
Fraction of light
beam orizontal position
11
ZDC centrality trigger layout
e.m.dissociation trigger
ADCs
CAEN V895
CAEN V512
CAEN N625
LHC tunnel
Rack CR4-X04
Q1
Q2
fan-in
PLU
fan-in
fan-out
discri
Q3
Q4
QC
ZNL
150 m
ZDC_MB ZDC_SC ZDC_CE
ZNR
to CTP
ZPL
ZPR
The electronics modules and the crates already
procured
12
ZDC readout layout
CR4-X04
CR4-X04
VME fpga
TRIG fpga
ADC CAEN V965 already procured
Analog Inputs (25 ch)
ZDCRC not yet available
VME Output Buffer 32 events deep
ACQ fpga
TTCrx
SIU
clear
gate
busy
optical fiber L1,L2
Delay gt5.5 ms without L0
to CTP
to LDC
from PLU

• ZDCRC readout controller (still to be defined)
  to receive L1,L2 trigger and to send data to DAQ
• VME card similar to the Dimuon Trigger Readout
  Controller (DARC)

13
ZDC e.m. dissociation trigger layout (L0)
LHC tunnel at 116 m from IP
Trigger crate UX25
Analog signal from ZN PMTc on RD26 side (2nd
anode output)
discri
air core cable
L0 to CTP

• The air core cable has to be chosen and procured
• The cable has to be as short as possible
• The discriminator and logic has to be put in one
  of the trigger crates

threshold window to select one spectator neutron
14
ZDC e.m. dissociation trigger layout (L1)
LHC tunnel
CR4-X04
ADCs
PLU
Q1
Q2
fan-in
discri
Q3
Q4
QC
ZNL
to CTP L1 ZDCEM
ZNR

• The electronics is sitted in the rack CR4-X04
• The thresholds in the discriminator select one
  spectator neutron on both side of IP
• All the electronic modues already procured

15
ZDC integration in the LHC tunnel

• Final design of the TDI (removable collimator)
• checked with simulation
• Insertion of new collimators (TCDD,TCLI,TCT) in
  the IR2 straight section but internal details not
  yet defined
• To be checked with simulation
• User requirements for the platform design defined
• Discussions about who should operate the movable
  platform is going on (ALICE or LHC machine? )

16
ALICE ZDC Planning
ZDC activities up to the installation
17
ZDC Milestones

• Construction of ZP2 31 October 2005
• Construction of ZEM 31 December 2005
• Test of ZP2 and ZEM 30 June 2006
• Installation into the tunnel 31 December 2006

18
Summary

• ZP1 has been built and tested
• Detector performances according to expectations
• and the ALICE requirements
• Construction of ZP2 will start in summer 2005
• Absorber plates already machined in Torino and
  quartz fibres ready to be cut and polished in
  Cagliari
• Assembly of ZP2 to be done in july at Cern (in a
  building to be found)
• The definitive project of the support platform
  has to start soon
• close interaction with CERN engineers to check
  the solutions