Transcript Document

95° LHCC Meeting – September 24, 2008
Status report
of the LHCf experiment:
preparation for data taking
Oscar Adriani
INFN Sezione di Firenze
Dipartimento di Fisica dell’Università degli Studi di Firenze
LHCf Physics Topics – Short summary!
 Experimental measurement:
– Precise measurement of g and p0 spectra in the very forward
region at LHC
 7 TeV + 7 TeV in the c.m. frame  1017 eV in the
laboratory frame:
– We can better simulate in the biggest’s world laboratory what
happens in nature when a Very High Energy Cosmic Ray interacts
in the atmosphere
 Why in the very forward region?
– Because the dominant contribution to the energy flux in the
atmospheric shower development is carried on by the very
forward produced particles
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A ‘practical’ approach
From the practical point of view LHCf’s measurements
will be used to calibrate the Monte Carlo codes heavily
used in the Cosmic Ray analysis
– VHECR energy spectra
– HECR Composition
Berezinsky 2007
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AGASA x 0.9
HiRes x1.2
Yakutsk x 0.75
Auger x1.2 (not enough)
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LHCf: location and detector layout
Detector I
Tungsten
Scintillator
Scintillating fibers
Detector II
Tungsten
Scintillator
Silicon mstrips
INTERACTION POINT
IP1 (ATLAS)
140 m
140 m
Beam line
Detectors should measure energy and position of g
from p0 decays
e.m. calorimeters with
position sensitive layers
Two independent detectors on both side of IP1
 Redundancy
 Background rejection (especially beam-gas)
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LHCf location
Detectors installed in the TAN region, 140 m
away from the Interaction Point, in front of
luminosity monitors
Here the beam pipe splits in 2
separate tubes.
Charged particle are swept
away by magnets!!!
We will cover up to y
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Detector #1
2 towers 24 cm long
stacked vertically with 5
mm gap
Lower: 2 cm x 2 cm area
Upper: 4 cm x 4 cm area
Impact point (h)
4 pairs of scintillating
fiber layers for tracking
purpose (6, 10, 32, 38
r.l.)
Absorber
22 tungsten layers
7mm – 14 mm thick
(W: X0 = 3.5mm, RM = 9mm)
16 scintillator layers
(3 mm thick)
Energy
Trigger and energy
profile measurements
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Detector # 2
We used LHC style
electronics and readout
Impact point (h) 2 towers 24 cm long stacked
on their edges and offset
from one another
4 pairs of silicon microstrip layers
(6, 12, 30, 42 r.l.) for tracking
purpose (X and Y directions)
Lower: 2.5 cm x 2.5 cm
Upper: 3.2 cm x 3.2 cm
16 scintillator layers
(3 mm thick)
Trigger and energy
profile measurements
Energy
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Absorber
22 tungsten layers
7mm – 14 mm thick (2-4 r.l.)
(W: X0 = 3.5mm, RM = 9mm)
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Final Detectors ready since 2007
Arm#2 Detector
Arm#1 Detector
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Installation
 Final installation was completed in January 2008
 No major problems have been found
– Quartz fiber for laser calibration has been re-installed
 Both Arm1 and Arm2 are working fine
 No additional noise is found in the detectors,
despite 200 m long power lines and signal cables
(for the scintillators)
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Detectors in place
Installation performed in two phases:
1. Pre-Installation (2007)
Baking out of the beam pipe (200 °C)
2. Final Installation (Jan 2008)
LHCf
Luminosity
Monitor (BRAN)
ATLAS ZDC
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Front Counter
 2 fixed Front Counters
were installed in front
of Arm1 and Arm2
 They will not move with
Arm1 and Arm2
 They are segmented in
2 x and 2 y slices
 Very useful to check the
beam quality and
hence decide to move
Arm1 and Arm2 in the
operating position from
the ‘garage’ position
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After the installation….
 After the installation was completed, a lot of work on:
– DAQ
• New VME board to increase DAQ rate up to > 1 KHz
• Integration of all the subsystem (Using MIDAS frame)
• Analyzer to check the data quality and online monitor
– Slow control software to control and monitor:
• Power supplies
• Manipulator
• Temperature monitor
– LHC interface
• New NIM style board (CIBU) to send ‘PERMIT’ to LHC (KILL the
beam in case of high rate)
• Handhshaking software signals (DIP standard) for Injection, Adjust
and Beam Dump
• LHCf Physics information (beam position, rate, background etc.)
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Synchronization with Atlas
 To have the possibility to identify the events common
with Atlas we implemented a synchronization method
based on the L1A signal generated by Atlas.
 We receive Atlas L1A and we store the time stamp of this
signal in our DAQ system.
 We can really correlate the Atlas events with the LHCf
ones!
Atlas Bunch ID – LHCf Bunch Id
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An Update on the 2007 SPS Beam Test
Test was very successful!!!!
 CERN : SPS T2 H4
Energy calibration of the
 August/September 2007
calorimeters
 Incident Particles
Spatial resolution of the
– Proton 150,350 GeV/c
tracking systems
– Electron 50, 100, 150, 200 GeV/c
Results were partially
– Muon 150 GeV/c
published on JINST:
2008 JINST 3 S08006
Setup
LHCf
Detector
Moving Table
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Silicon
Tracker
Trigger
Scintillator
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Energy Resolution
2 x 2 cm2 tower
2.5 x 2.5 cm2 tower
Energy resolution < 3% even
for the smallest tower!
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350 GeV Proton beam
p0 reconstruction
g
Not in scale!
g
Carbon target (3 cm)
in the slot used for beam monitor
9.15 m
Arm1
>107 proton on target (special setting from the SPS people)
Dedicated trigger on both towers of the calorimeter has been used
Calorimeters
Shower Profile @ First SciFi Layer
40mm
X
Egamma=18GeV
Y
20mm
Egamma=46GeV
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X
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p0 mass reconstruction
 250 p0 events triggered (in a quite big background) and on disk
(MeV)
 Main problems:
– low photon energy (≥ 20
GeV)
– Direct protons in the towers
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Dm ~ 8 MeV
Dm/m ~ 6%
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ARM1 Position resolution
sx=172 mm
σx[mm]
Number of event
200 GeV electrons
x-pos[mm]
sy=159 mm
σy[mm]
Number of event
E[GeV]
y-pos[mm]
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E[GeV]
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ARM2 Position
Resolution
Position Resolution X Side
120
Data
100
Resolution (microns)
200 GeV electrons
sx=40 mm
Simulation Spread Out
80
60
40
20
0
0
50
100
150
200
250
Energy (GeV)
x-pos[mm]
Position Resolution Y Side
160
140
Data
Simulation Spread Out
sy=64 mm
Resolution (microns)
120
100
80
60
40
y-pos[mm]
Alignment has been taken into account
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20
0
0
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50
100
150
Energy (GeV)
200
250
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From the 2007 SPS beam test
analysis we can conclude that the
detectors fulfill the requirements
to reach the physics goals
indicated in the TDR
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Preparation for data taking
The LHCf control room has been prepared and fully
equipped in the Atlas area
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Furnitures
Telephones
Air conditioner
Network
Computers
Printers
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Dummy event
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Communications with LHC
LHCf sends signals to LHC through the DIP system.
Link have been tested and it works fine!
Important for machine tuning!
 Experimental status (On/Off, Gain, etc.)
 Detector position (Garage/Operating, position in mm, etc.)
 Luminosity rate (Single and Double Arm)
–
–
–
–
Front Counter rate (single Arm, double Arm coincidence)
Small tower rate (single Arm)
Big tower rate (single Arm)
Double Arm coincidence rate (FC.AND.Towers in opposite sides)
 Horizontal and Vertical position of the Beam (every 10000 events or in
the whole RUN)
 Injection Inhibit
 Handshaking signals (Injection, Adjust, Beam Dump)
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We are ready for data taking
 On September 10 we observed some signals on Front
Counters, with Arm1 and Arm2 in garage position for
safety reasons
– That day the Atlas BPTX signal was still not available
(no info on the real bunches in the Atlas zone)
 On September 11 Atlas gave us the synchronized BPTX
signals, and we could take Front Counter data by using
this signal (still in garage position)
 We are measuring Beam-Gas from the Beam2 on Arm1
side
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Front Counter signals
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Conclusions
 A lot of work has been done in 2008
 Installation completed
 Preparation for running completed
 Identification of events common to Atlas and
LHCf is ok
 First beam gas events acquired
 We are ready to send our info to LHC for beam
tuning
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Spare slides
The LHCf Collaboration
CERN
D.Macina, A.L. Perrot
USA
LBNL Berkeley:
W. Turner
FRANCE
Ecole Politechnique Paris:
M. Haguenauer
SPAIN
IFIC Valencia:
A.Fauss, J.Velasco
ITALY
Firenze University and INFN:
O.Adriani,, L.Bonechi, M.Bongi,
G.Castellini, R.D’Alessandro,
P.Papini, S. Ricciarini, A. Viciani
Catania University and INFN:
A.Tricomi
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JAPAN:
STE Laboratory Nagoya University:
K.Fukui,Y.Itow, T.Mase,
K.Masuda,Y.Matsubara, H.Menjo,T.Sako,
K.Taki, H. Watanabe
Waseda University: K. Kasahara, M. Mizuishi,
Y.Shimizu, S.Torii
Konan University:Y.Muraki
Kanagawa University Yokohama: T.Tamura
Shibaura Institute of Technology: K. Yoshida
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Radiation Damage Studies
Scintillating fibers and scintillators
• Expected dose: 100 Gy/day at 1030 cm-2s-1
• Few months @ 1030 cm-2s-1: 10 kGy
• 50% light output
• Continous monitor and calibration with
Laser system!!!
30 kGy
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LHCf : Monte Carlo discrimination
106 generated LHC interactions 
1 Minute exposure@1029 cm-2s-1 luminosity
Discrimination between various models
is feasible in a very short time
Quantitative
discrimination with
the help of a properly
defined c2
discriminating
variable based on the
spectrum shape
(see TDR for details)
5% Energy resolution
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‘Analysis’ of Beam Gas events
We got 116 FC triggers in 8.275.034 BPTX: Nt=116
2.109 protons/bunch
Total # of protons: Np=1.7 x 1016
We try to estimate the gas density r from this rate:
Nt=Np* L * s * r
L=effective lenght ~ 100 m
s=Cross section ~ 80 mbarn = 80 x 10-31 m2
We find: r = 8.5 x 1012 H/m3 = 4.2 x 1012 H2/m3
From the LHC Project Report #783: r = 1012 H2/m3
From the pressure measurement in April 2008: r ~ 1012 H2/m3
~ CONSISTENT!!!!!!!!!!!!!
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Estimate of the background
 beam-beam pipe
 E γ(signal) > 200 GeV, OK
background < 1%
 beam-gas
 It depends on the beam condition
background < 1% (under 10-10 Torr)
 beam halo-beam pipe
 It has been newly estimated from the beam loss rate
Background < 10% (conservative value)
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LHCf performances: p0 geometrical
acceptance
Arm #1
Arm #2
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LHCf performances: energy spectrum of p0
Typical energy resolution of g is 3 % at 1 TeV
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Transverse projection in TAN slot
ARM1: Maximization of the
acceptance for vertical beam
displacement (crossing
angle>0)
ARM2: Maximization of the
acceptance in R (distance
from beam center)
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LHCf: model dependence of
neutron energy distribution
Original n energy
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30% energy resolution
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Monte Carlo
Energy Resolution
N Particles
Test Beam
Distance from Edge
Energy distribution is
corrected for leakage
MC predicts that the
leakage is energy independent!
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Simulation vs
Data
150 GeV m
Energy released in the
4° scintillation layer
100 GeV e-
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Simulation is very
well understood!
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While waiting for collisions….
Proton
A short comment on new
models:
PICCO, EPOS
Very big interest in LHCf data
and in this physics field
Drescher, Physical Review D77,
056003 (2008)
p0
Neutron
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ARM2-Silicon Energy Resolution
200 GeV electrons
SPS beam test data
DE/E ~ 12%
Total energy measured in silicon (ADC)
By looking only at the silicon energy measured, we have an energy resolution ~ 10%!!!!!
We can use it as a check for the radiation damage of the scintillators
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