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LHCf Technical Design Report
CERN-LHCC-2006-004
LHCF-TDR-001
7 February 2006
Measurement of Photons and Neutral Pions in the
Very Forward Region of LHC
O. Adriani(1), L. Bonechi(1), M. Bongi(1), R. D’Alessandro(1), D.A. Faus(2),
M. Haguenauer(3), Y. Itow (4), K. Kasahara(5), K. Masuda(4), Y.
Matsubara(4), H. Menjo(4), Y. Muraki(4), P. Papini(1), T. Sako(4), T.
Tamura(6), S. Torii(7), A. Tricomi(8), W.C. Turner(9), J. Velasco(2) , K.
Yoshida(6)
The LHCf collaboration
(1) INFN Firenze, Univ. di Firenze, Firenze, Italy
(2) IFIC, Centro Mixto CSIC-UVEG, Valencia, Spain
(3) Ecole-Polytechnique, Paris, France
(4) STE laboratory, Nagoya University, Nagoya, Japan
(5) Shibaura Institute of Technology, Saitama, Japan
(6) Kanagawa University, Yokohama, Japan
(7) RISE, Waseda Univ., Tokyo, Japan
(8) INFN Catania, Univ. di Catania, Catania, Italy
(9) LBNL, Berkeley, California, USA
March 22, 2006
LHCf Technical Design Report
O. Adriani
Highlight of the talk
1. Short ‘history’
2. Review of physics
3. Detector overview and background study (after
November 16th LHCC)
4. Progress report on cabling, safety, installation,
trigger, luminosity measurement, etc
5. Possible running scenario
6. Summary
Many important technical aspects can not be covered in this
presentation  TDR for details
March 22, 2006
LHCf Technical Design Report
O. Adriani
Letter Of Intent: May 2004
Technical report: September 2005
Technical Design Report: February 2006
LHCC October 2005 comments:
•The physics goals are worthwhile and the proposed experiment appears suited to achieve them
•A few key issues require immediate consideration, and documentation in the update of the TP:
•establish official contact with the relevant structures in the AT/AB departments,
as well as in ATLAS etc…
•appoint a technical coordinator (possibly located at CERN?)
•consider and document safety issues
•On the other hand: the TP is not sufficiently detailed and fails to provide a solid and
compelling evidence that the above expectations are justified
TDR was released to answer to these questions
March 22, 2006
LHCf Technical Design Report
O. Adriani
Xmax(g/cm2)
Main problems in
High Energy Cosmic Rays (E>1015eV)
1. Composition
2. Spectrum / GZK Cutoff
March 22, 2006
LHCf Technical Design Report
Energy (eV)
O. Adriani
Development of atmospheric
showers
Simulation of an
atmospheric shower due
to a 1019 eV proton.
• The dominant contribution to the energy flux is in the very forward region
(  0)
• In this forward region the highest energy available measurements of p0
cross section were done by UA7 (E=1014 eV, y = 5÷7)
The direct measurement of the p production cross section as
function of pT is essential to correctly estimate the energy of
the primary cosmic rays (LHC: 1017 eV)
March 22, 2006
LHCf Technical Design Report
O. Adriani
Experimental Method:
2 independent detectors on both sides of IP
Detector I
Tungsten
Scintillator
Scintillating fibers
Detector II
Tungsten
Scintillator
Silicon mstrips
INTERACTION POINT
140 m
140 m
Beam line
1. Redundancy
2. Background rejection (especially beam-gas)
IP1 was definitely chosen in October 2005
March 22, 2006
LHCf Technical Design Report
O. Adriani
•Here the beam pipe splits
in 2 separate tubes.
•Charged particle are swept
away by magnets!!!
•We will cover up to y 
March 22, 2006

Detectors will be installed
in the TAN region, 140 m
away from the Interaction
Point, in front of luminosity
monitors
LHCf Technical Design Report
O. Adriani
The TAN and LHCf
box ~ (15×15×40) cm3
manipulator
marble
shielding
boxes for
DAQ electronic
March 22, 2006
LHCf Technical Design Report
O. Adriani
ARM #1 detector
scintillating fibers
tungsten layers
- 2 towers (2.02.0cm2 and 4.04.0 cm2)
• ~47 r.l. (22  2.1 r.l. tungsten layers)
Energy
• 16 scintillator layers (3 mm thick)
- 4 pairs of scintillating fiber layers for tracking purpose
(two orthogonal directions)
March 22, 2006
LHCf Technical Design Report
scintillators
Impact point (h)
O. Adriani
We used LHC style
electronics and readout
silicon layers
ARM #2 detector
- 2 towers (2.52.5cm2 and 3.53.5 cm2)
• 44 r.l. (22  2 r.l. tungsten layers)
• 16 scintillator layers (3 mm thick)
- 4 pairs of silicon microstrip layers for
tracking purpose (X and Y directions)
Energy
Impact point (h)
See TDR for details…
scintillators
tungsten layers
March 22, 2006
LHCf Technical Design Report
O. Adriani
Transverse projection
of detector #1 in the TAN slot
March 22, 2006
LHCf Technical Design Report
O. Adriani
Transverse projection
of detector #2 in the TAN slot
March 22, 2006
LHCf Technical Design Report
O. Adriani
LHCf physics measurements
1.
2.
Single photon spectrum
p0 fully reconstructed (1 g in each tower)
p0 reconstruction is an important tool for energy
calibration (p0 mass constraint)
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Basic concept:
minimum 2 towers (p0 reconstruction)
Smallest tower on the beam (multiple hits)
Dimension of the tower  Moliere radius
Maximum acceptance (given the LHC constraints)
Simulation is used to understand the physics performances
Beam test in Summer 2004 (Energy resolution)
March 22, 2006
LHCf Technical Design Report
O. Adriani
Development of showers in Arm #2
E γ= 500 GeV
Fluka based
simulation
March 22, 2006
LHCf Technical Design Report
O. Adriani
Position resolution of Arm #2 calorimeter
7 mm for 1.8 TeV photons
March 22, 2006
LHCf Technical Design Report
O. Adriani
Some runs with LHCf vertically shifted few cm
Single
g
geometrical
acceptance
will allow to cover the whole kinematical range
March 22, 2006
LHCf Technical Design Report
O. Adriani
g-E >plane
A
vertical beam
crossing
0
will
Acceptance
map
on PTangle
γ
increase the acceptance of LHCf
140
March 22, 2006
LHCf Technical Design Report
Beam crossing
angle
O. Adriani
Monte Carlo g ray energy spectrum
(5% Energy resolution is taken into account)
106 generated LHC interactions  1 minute exposure
Discrimination between various models is feasible
Quantitative
discrimination with
the help of a
properly defined c2
discriminating
variable based on the
spectrum shape
(see TDR for details)
March 22, 2006
LHCf Technical Design Report
O. Adriani
p0 geometrical
acceptance
Arm #2
Arm #1
March 22, 2006
LHCf Technical Design Report
O. Adriani
Energy spectrum of π0 expected from different models
(Typical energy resolution of g is 3 % at 1TeV)
March 22, 2006
LHCf Technical Design Report
O. Adriani
p0 mass resolution
Arm #1
DE/E=5%
200 mm spatial resolution
Dm/m = 5%
March 22, 2006
LHCf Technical Design Report
O. Adriani
Model dependence of neutron energy distribution
Original n energy
March 22, 2006
LHCf Technical Design Report
30% energy resolution
O. Adriani
Results of the beam test at H4 line
March 22, 2006
LHCf Technical Design Report
O. Adriani
Summary 1
• We will be able to measure π0 mass with ±5%
resolution.
• We will be able to distinguish the models
by measurements of π0 and γ
• We will be able to distinguish the models
by measurements of n
• Beam crossing angle ≠0 and/or vertical shifts of
LHCf by few cm will allow more complete physics
measurements
March 22, 2006
LHCf Technical Design Report
O. Adriani
Estimation of the background
• beam-beam pipe
 answered (on Nov.16),
E γ(signal) > 200 GeV, OK
background < 1%
(see details in TDR)
• beam-gas
 answered (on Nov.16)
It depends on the beam condition
background < 1% (under 10-10 Torr)
(see details in TDR)
• beam halo-beam pipe
 It has been newly estimated from the beam loss rate
Background < 10% (conservative value)
March 22, 2006
LHCf Technical Design Report
(see details in TDR)
O. Adriani
Background from the beam pipe
March 22, 2006
LHCf Technical Design Report
O. Adriani
March 22, 2006
LHCf Technical Design Report
O. Adriani
Support from CERN for Integration
We had (and we will have!) continuous meetings with CERN teams
•General : TS/LEA
•Integration: TS/IC
•Cabling: TS/EL
•Cooling: TS/CV
Takashi Sako: Technical coordinator
•Survey (cabling): TS/SU
•Safety: SG
•Radiation protection: SC/RP
•ATLAS, BRAN, ZDC teams
A very useful TAN integration
workshop has been organized on
March 10 at CERN (TS/LEA).
All the involved groups were present!!!!
Engineering Change Request (ECR) has been
submitted and approved last week:
•Machine people are well informed about LHCf
•No problems foreseen for the LHCf installation at the LHC startup
•Main item to be discussed is the BRAN (LUMI) interference (see later)
March 22, 2006
LHCf Technical Design Report
O. Adriani
Rack, data taking and trigger
*Two racks will be located at Y26-05.A1 and Y27-05.A1 at
USA15 hall of ATLAS counting room
*The trigger signal will be created after 1.4 msec of the
beam crossing
1st level trigger
2nd level trigger
March 22, 2006
LHCf Technical Design Report
O. Adriani
Cables
• TS/LEA is fully aware of
the cables stuff
• Demande Installation
Cable (DIC) has been
submitted
• The order is under way
• Cables will be pulled in the
July-September period
See TDR for details
March 22, 2006
LHCf Technical Design Report
O. Adriani
Radiation Safety
• We have estimated the total radiation dose
and activation of LHCf installed in the TAN
• The activation after 30 days of operation
and 1 day cool-down at ℒ ≈ 1030 /cm-2sec-1 is
10-3 – 10-2 mSV/hr
• Remote handling procedures may not be
needed
• We are in contact with SC/RP peoples
March 22, 2006
LHCf Technical Design Report
O. Adriani
Installation plan
A detailed installation plan has been agreed with TS/LEA
Arm #1: 128 days from May 2006 to November 2006
•Cables tray
•Cables
•Detector
•Manipulator
•Electronics
•Tests
Arm #2: 210 days from May 2006 to February 2007, similar to #1
LHCf Arm #1 and #2 will be ready to
take the first LHC data…..
(Beam test of the complete Arm #1 and part of the
Arm #2 is foreseen August 24th, September 3rd at SPS)
March 22, 2006
LHCf Technical Design Report
O. Adriani
LHCf and LUMI monitor (BRAN)
LUMI monitor (BRAN) inside TAN is beyond LHCf (replacing 4th copper bar)
IP1
Cu Bar / ZDC
LHCf
Lumi
Cu Bar / ZDC
LHCf
Lumi
LHCf  44 X0 thickness
But the thickness is not uniform (diamond shaped towers, no material outside towers)
LUMI Monitor see different thickness of material in different geometrical regions 
• different response as function of the impact point position (calibration is required)
• reduction of the number of neutral particles hitting BRAN
• possible dependence of the detector response as function of the beam position?
We are studying the problem of the LHCf effect on LUMI together with W.C. Turner and
his group from LBNL. CERN LHC and ATLAS people are informed about these studies (see
TAN integration workshop as last example)
March 22, 2006
LHCf Technical Design Report
O. Adriani
Effect of LHCf on BRAN measurement
The effect of LHCf on BRAN measurements has
been studied in the last months by simulation
– Reduction of shower particles at BRAN
– Position dependence on beam displacement
(question from machine peoples: if we shift by 1 mm the
real beam, does the center of the measured neutral
energy shifts by 1 mm?)
Answer:
 If beam displacement is < a few mm, difference is < 10%
 LHCf itself can provide the center of neutral flux
 LHCf can give some info on Luminosity measurement
March 22, 2006
LHCf Technical Design Report
O. Adriani
BRAN response vs beam position
reduction factor for BRAN:
# of neutral hadrons in the LHCf aperture /
Typical reduction factor: 0.3
# of neutral hadrons in the whole aperture
(inelastic interactions generated with DPMJET3 model)
Arm #1
March 22, 2006
Arm #2
LHCf Technical Design Report
H.Menjo
O. Adriani
BRAN response vs beam position (2)
Relative change of the reduction factors for BRAN with respect to the
nominal value (center of the beam: nominal one)
If the position of beam center stays within a few mm
from the beam-pipe center, the reduction factors do
not change more than 10%
Arm #1
Arm #2
1 x 1
cm2
March 22, 2006
1 x 1
cm2
LHCf Technical Design Report
H.Menjo
O. Adriani
Determination of neutral flux center by LHCf
LHCf can measure (and provide to LHC) the center
of neutral flux from the collisions
particles
Position sensitive layers
Beam test result
If the center of the
neutral flux hits LHCf
 << 1 mm resolution
March 22, 2006
s ~ 200mm
LHCf Technical Design Report
O. Adriani
Summary 2
• LHCf can do the proposed physics
measurements (background is under control)
• Integration with CERN infrastructures and
other groups involved is well established
• The interference with BRAN/LUMI
measurement is under study; a ‘smooth’ solution
seems to be feasible
• LHCf can provide on-line useful information to
machine people (Relative luminosity, beam
position, beam-gas rate etc.)
Important issue to be considered in detail
from now on
March 22, 2006
LHCf Technical Design Report
O. Adriani
Optimal LHCf run conditions
Beam parameter
Value
# of bunches
≤ 43
Bunch separation
> 2 msec
Crossing angle
0 rad
140 mrad downward
Luminosity per
bunch
< 2 x 1028 cm-2s-1
Luminosity
< 0.8 x 1030 cm-2s-1
Bunch intensity
4x1010 ppb (b*=18m)
1x1010 ppb (b*= 1m)
• Beam parameters used
for commissioning are
good for LHCf!!!
( No radiation problem for 10kGy by a “year” operation with this luminosity )
March 22, 2006
LHCf Technical Design Report
O. Adriani
From H. Burkhardt TAN workshop presentation
March 22, 2006
LHCf Technical Design Report
O. Adriani
LHCf possible running scenario
• Phase-I
– Parasite running during the early stage of LHC
commissioning in 2007
– Remove the detector when luminosity reaches
1030cm-2s-1 level for radiation reason and reinstall
the 3 Cu bars (no activation problems)
• Phase-II
– Re-install the detector at the next opportunity of
low luminosity run after removal of Cu bars
(activated to 10-1 mSv/hr, manipulator?)
• Phase-III
– Future extension for p-A, A-A run with upgraded
detectors.
Detailed running scenario should be discussed and agreed with
LHCC, Machine people, Atlas people….
March 22, 2006
LHCf Technical Design Report
O. Adriani
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Detector # 1
Detector#2
Tungsten
Japan
Mechanics
Japan
Plastic Scintillators
Japan
Scintillating fibers
Japan
Silicon sensors
----------Photomultipliers for scintillator Japan
Multianode photomultipliers for fibers
Japan
Preamplifiers for silicon
----------Hybrid and Kapton for silicon ----------Readout electronics for fibers (VA based)
Japan
Readout electronics for silicon ----------VME Interface board for fibers Japan
VME Interface board for silicon ----------VME ADC boards for scintillators
Japan/INFN
VME crate
Japan
Low voltage Power Supply
Japan
High voltage Power Supply for scintillators
Japan
High voltage Power Supply for fibers
Japan
March 22, 2006
Japan
Japan
Japan
----------INFN
Japan
----------INFN
INFN
----------INFN
----------INFN
Japan/INFN
INFN
INFN
Budget
share table
Contributions from
different countries
Japan:
600KCHF
Italy:
300KCHF
France: under negotiation
Japan/INFN
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LHCf Technical Design Report
O. Adriani
Concluding Remarks
• LHCf physics measurements are extremely
useful for cosmic ray physics (see LOI 2004)
• A huge work has been done to complete the
TDR, answering to the LHCC and referees
comments
• The detectors have been carefully optimized
• The integration with other activities possibly
interfering with LHCf is well established
(ATLAS, BRAN/LUMI, TAN related
experiment, safety, cabling etc.)
• ECR has been approved last week
• LHCf will be ready to take the first LHC data…
March 22, 2006
LHCf Technical Design Report
O. Adriani