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LHCf: il run con ioni (e i due nuovi risultati …). Oscar Adriani. 3 Aprile 2012. Some historical remarks. LHCf expression of interest for proton/Lead 2012 run Presentation at the LPCC meeting on October 17 th , 2011 Contact with Atlas management - PowerPoint PPT Presentation
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LHCf: il run con ioni(e i due nuovi risultati…)
Oscar Adriani
3 Aprile 2012
Some historical remarks LHCf expression of interest for proton/Lead 2012 run
Presentation at the LPCC meeting on October 17th, 2011 Contact with Atlas management
Letter of Intent submitted to LHCC on December 4th, 2011 CERN-LHCC-2011-015/LHCC-I-021 04/12/2011
Approved by LHCC in December 2011! The Committee has independently verified
the support of the ATLAS Collaboration, and recommends the acceptance of the Letter of Intent.
And formal approval by RB practically obtained in March 2012!
The plan for LHCf to run during proton-Pb run was agreed by the LHCC and endorsed by the Research Board
Global LHCf physics programLHCf measurement for p-Pb interactions at 3.5TeV proton energy could be easily and finely integrated in the LHCf global campaign.
Period Type Beam energy
LAB proton Energy
(eV)Detector
2009 p - p 450+450 GeV 4.3 1014 Arm1+Ar
m22009/20
10 p - p 3.5+3.5 TeV 2.6 1016 Arm1+Ar
m2
2012 p – Pb 3.5 TeV proton E 1016 Arm2
2014 p - p 7+7 TeV 1017Arm1+Ar
m2 upgraded
We are simulating protons with energy Ep = 3.5 TeV Energy per nucleon for ion is
“Arm2” geometry considered on both sides of IP1 to study both p-remnant side and Pb-remnant side
No detector response introduced yet (only geometrical considerations and energy smearing)
Results are shown for DPMJET 3.0-5 and EPOS 1.99, 107 events each
140 m 140 m
p-beam
Pb-beam
“Pb-remnant side”
“p-remnant side”
nTeV/nucleo 38.1 pN EAZ
E
What LHCf can measure in the p+Pb run (1)E, pT, spectra of neutral particles
Proton-remnant side - multiplicity
n
Small tower Big tower
Proton-remnant side – photon spectrumSmall tower Big tower
Proton-remnant side – neutron spectrumSmall tower Big tower
35% ENERGY RESOLUTION IS CONSIDERED IN THESE PLOTS
Proton remnant side – Invariant cross section for isolated -rays
What LHCf can measure in the p+Pb run (2)Study of the Nuclear Modification Factor
Nuclear Modification Factor measured at RHIC (production of p0): strong suppression for small pt at <>=4.
LHCf can extend the measurement at higher energy and for >8.4Very important for CR Physics
Phys. Rev. Lett. 97 (2006) 152302
Proton-remnant side – p0
We can detect p0!
Important tool for energy scale
And also for models check…..
Lead-remnant side – multiplicityPlease remind that EPOS does not consider Fermi motion and Nuclear Fragmentation
n
Small tower Big tower
Some estimations based on reasonable machine parameters…. Considering machine/physics parameters:
Number of bunches, n = 590 (150 ns spacing) Luminosity up to 1028 cm-2s-1 Interaction cross section 2 barn
PILE-UP effect Around 310-3 interactions per bunch crossing 1% probability for one interaction in 500 ns (typical time
for the development of signals from LHCf scintillators after 200 m cables from TAN to USA15)
Some not interacting bunches required for beam-gas subtraction
Beam gas first estimation indicate no problem Beam Gas/Beam Beam = 3.10-4
Minimum required number of collision: Ncoll = 108 (factor 10 more statistics wrt shown plots) Integrated luminosity Lint = 50 mb-1
2106 single photons expected on p-remnant side
35000 p0 expected on same side
Assuming a pessimistic scenario with luminosity L = 1026 cm-2s-1 : Minimum running time for physics t = 140 h
(6 days)
… and required statistics to complete the p/Pb physics run
Once we have been approved…. We have to do the run!!!!! Technical points:
Installation issues Manpower for Installation, setup and data taking
Please note that Arm2 is ‘more italian than japanese’…. Money for missions (Sblocco SJ, see referee presentation)
4days slot to install
>3 weeks of run
Preparation for 2012 p-Pb run
We have installed multi-pole connectors in tunnel (02/12) We have checked that optical fibers are ok (not damaged by
radiation) (02/12) We are producing a new transportation frame for Arm2+electronics 1-2 experts will stay at CERN from September for DAQ
commissioning One month of 24 hours per day shifts (minimum 8 persons at Cern
for one month, few from Japan and few from Italy) Big manpower is requested…. Please note that Atlas ZDC have already been removed in February
2012, since new detectors are being produced. The hadronic part will be installed behind LHCf on Arm2 side, and em+had part on the other side
Sinergies between LHCf and Atlas are encouraged by LHCC We are working on it
Arm2
Pb
pIP8IP2
IP1Arm2
16
New configuration Fixing the three sub-systems together
New base plate
Lead block for balance
A fast spot on 2 new analyses
Submitted to PLB
Measured 900 GeV single spectrum
Type-I Type-IIType-I
Type-II
0 3500 0 3500Ep0(GeV) Ep0(GeV)
PTp0
(GeV
/c)
0
1 1
0
sM=3.7%
LHCf 7TeV p0 analysis
20
Combined type-I p0 pT spectra (invariant cross section)
DPMJET 3.04 QGSJETII-03 SIBYLL 2.1 EPOS 1.99 PYTHIA 8.145Sys+stat
PTp0(GeV/c)0 0.6
1/N i
nt Ed
3 N/d
p3 1
10-4
8.9<y<9.0 9.0<y<9.2 9.2<y<9.4
9.4<y<9.6 9.6<y<10.0 10.0<y<11.0
Recent Publication (2011-2012)Title journalMonte Carlo study of forward pi0 production spectra to be measured by the LHCf experiment for the purpose of benchmarking hadron interaction models at 10(17)-eV.
Astropart.Phys. 34 (2011) 513
Measurement of zero degree single photon energy spectra for s√ = 7-TeV proton-proton collisions at LHC.
Phys.Lett. B703 (2011) 128
Study of radiation hardness of Gd(2)SiO(5) scintillator for heavy ion beam (Japan only) JINST 6 (2011) T09004 Luminosity determination in s**(1/2) = 7-TeV proton collisions using the LHCf front counter at LHC. JINST 7 (2012) T01003 Calibration of LHCf Calorimeters for Photon Measurement by CERN SPS Test Beam
NIM. A671 (2012)129
Measurement of zero degree photon energy spectra for √s = 900GeV proton-proton collisions at LHC
Submitted to PLB
Measurement of transverse momentum spectra of forward neutral pions for root s=7TeV proton-proton collisions at LHC
To be submitted
LHCf detector performance during the 2009-2010 LHC run In preparation
On-going analysis activity and plan
On going activity 7TeV hadron energy spectra g Inelasticity
Italian main analysis task for the near future Full analysis of single (larger , pT, invariant cross
section) Full analysis of p0 (Type-II p0) Feed back to the models and air shower experiments
Future plans Strange particles (Lgp0n, Ksg2p0(4))
Spares slides
Combined type-I p0 pT spectra
Radiation hardness of GSO
No decrease up to 1 MGy
+20% increase over 1 kGy (τ=4.2h recovery)
2 kGy is expected for 350nb-1 @ 14TeV pp)
1 kGyNot irradiated ref. sample
Irradiated sample
τ~4.2h recovery
K. Kawade et al., JINST, 6, T09004, 2011
Dose rate=2 kGy/hour(≈1032cm-2s-1)
Photons on the proton remnant side Photon energy distrib. in different intervals at sNN
= 7 TeV Comparison of p-p / p-N / p-Pb Enhancement of suppression for heavier nuclei
case QGSJET II-04 SIBYLL 2.1p-p
p-Np-Pb
All s8.81<<8.99
>10.94
Courtesy of S. Ostapchenko
Lead-remnant side – neutron spectrumSmall tower Big tower
35% ENERGY RESOLUTION IS CONSIDERED IN THESE PLOTS
GSO property(EJ260: plastic scintillator used in the current LHCf detectors)
GSO EJ-260density(g/cm3) 6.71 1.023
r.l.(cm) 1.38 14.2decay time(ns) 30-60 9.6
Fluorescence(NaI=100) 20 19.6
λem(nm) 430 490Refractive(@λem) 1.85 1.58
tolerance(Gy) 106 100melting point(℃) 1950 ー
Fast among inorganic scintillators
Best in the known scintillators
Identical to the current scintillators
Similar to the current scintillators
Heavy; reason to reduce 3->1mm
Light collection may differ
Uniformity test using C beam at HIMAC(preliminary results from quick analysis)
PMT via fiber bundle
PMT via fiber bundle
No particle due to the beam pipe
• Scan examples for a 20mmx20mm and a 40mmx40mm GSO plates
• All scintillators of Arm1 were mapped by C beam
• Similar uniformity to the current detector is obtained
mm
mm mm
mm
New structure
GSO bar bundle and quartz fiber light guide
GSO plate and light guide packed in a new holder
GSO plates and bars as calorimeters, but without Tungsten absorber layers
GSO bars cross talk and attenuation
Attenuation and cross talk are acceptable to determine the position of single particle shower and multihit identification
For multihit analysis, further study is necessary Paint between the bars reduces cross talk, but worsens attenuation and its bar-
to-bar variation
No paint between bars
-30%/35mm
10%
0%
Irradiated bar (100%)
Attenuation along the longest 40mm bar Cross talk
Estimation of Beam Gas background Input from p-p collisions (Data set used for the photon paper).
Luminosity per bunch (L/n) : 2x1028 cm-2s-1/bunch Intensity per bunch (I/n) : 2x1010 protons/bunch Total detected events in 25mm tower at non-bunch crossing : 101 photon events (for
non crossing bunches) DAQ live time : ~ 8x103 sec -> Event rate of beam gas per bunch = 101/8000/3 = 0.004 Hz
Inputs from p-Pb (assumptions) Luminosity per bunches (L/n) : 1.7x1025 cm-2s-1/bunch (L=1028, n=590) Inelastic cross section : 2 barn Expected collision rate : 34 Hz Expected photon detection rate in 25mm : 0.34 Hz (assuming acceptance=0.01)
Estimation of beam-gas background for p-Pb Assuming as the optics for p-Pb is same as one for p-p (same beta, same emittance),
the relative intensity is estimated by using L/n. (I/n)pPb / (I/n)pp ~ 0.03 The beam-gas background rate should be proportional to the intensity per
bunc, so it is estimated as 0.03 x 0.004 Hz = 10-4 Hz
As conclusion, the N/S in p-Pb is estimated as 10-4 / 0.34 = 3x10-4 Negligible!!!!
Few details about the LHCf Arm2 detector
Performances Energy resolution (> 100 GeV): < 3% for 1 TeV photons and 30% for neutrons Position resolution for photons: 40μm (Arm#2)
Sampling and imaging E.M. calorimeter Absorber: W (44 r.l , 1.55λI )
Energy measurement: plastic scintillator tiles 4 tracking layers for imaging: XY-Silicon strip(Arm#2) Each detector has two calorimeter towers, which allow to reconstruct p0 Front Counters
• thin scintillators 80x80 mm2 • monitoring of beam condition •Van der Meer scan 25mm
32mm
Arm2
LHCf physics program for p-Pb run
Important information for the study of the interaction of UHECR in the Earth atmosphere Comparison with hadronic interaction models Study of the Nuclear Modification Factor Inelasticity
Precise measurement of of E, and pT distributions for pseudo-rapidity > 8.4 both for p and Pb remnant Single Neutral pions Neutrons
WHY
HOW
Lead-remnant side – photon spectrumSmall tower Big tower
LHCf plans for the p/Pb run We will run with only one detector
Arm2 (W/scint. e.m. calorimeter + m-strip silicon) Only on one side of IP1 (on IP2 side, compatible
with the preferred machine setup: Beam1=p, Beam2=Pb)
Minimal interference with Atlas Installation during the technical
shutdown at the end of the p/p 2012 run