Chiara Oppedisano for the NA60 Collaboration - PowerPoint PPT Presentation

Slide1 l.jpg
Download
1 / 16

The NA60 experiment at the CERN SPS first results and future perspectives. Chiara Oppedisano for the NA60 Collaboration. Study of prompt dimuon and charm production with proton and heavy ion beams at the CERN SPS. Detector concept and physics programme Dimuon production in p-A collisions

I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.

Download Presentation

Chiara Oppedisano for the NA60 Collaboration

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Slide1 l.jpg

The NA60 experiment at the CERN SPS

first results and future perspectives

Chiara Oppedisano

for the NA60 Collaboration

Study of prompt dimuon and charm productionwith proton and heavy ion beams at the CERN SPS

  • Detector concept and physics programme

  • Dimuon production in p-A collisions

  • Charged particle pseudorapidity densities in Pb-Pb collisions

  • Future perspectives

C. Oppedisano


Detector concept l.jpg

Detector concept

MUON SPECTROMETER

~1m

Fe

wall

Tracking MWPCs

Muon filter

TARGET AREA

Toroidal Magnet

ZDC and

Quartz Blade

Trigger

hodoscopes

GOAL  accurate measurement of muon kinematics

Hadron absorber + muon spectrometer (NA50)  no information at vertex level to distinguish prompt from decay muons

VERTEX TELESCOPE  matching tracks in muon spectrometer and in vertex spectrometer

MAGNETIC FIELD measurement of muon track momentum at vertex

BEAM TRACKER  measurement of interaction point to determine impact parameter of muon tracks

Dipole field2.5 T

TARGET

BOX

MUON FILTER

BEAM

BEAMTRACKER

IC

TELESCOPE

C. Oppedisano


Beam tracker and target system l.jpg

Beam tracker and target system

  • BEAM TRACKER

  •  Silicon micro-strip detectors

  • 2 x-y stations upstream of target box

  • cryogenic detector (T = 130K)

  •  radiation hardness

  • 20 mm resolution on transverse

  • coordinates of interaction point

Online monitoring of beam profile  Pb @ 20 A GeV

  • TARGET SYSTEM

  • Proton beam Be, In and Pb targets

  • same beam normalization for all the nuclear targets

  • Ion beams  several thin sub-targets

  • interaction rate comparable to a thick target

  • reduced material traversed by muon in the angular acceptance of muon spectrometer

C. Oppedisano


Vertex telescope l.jpg

Vertex telescope

  • p-A collisions Silicon MICROSTRIP and PIXEL detectors

  • sensors divided in regions of variable strip pitch and length

  •  occupancy <3%

  • 16 microstrip planes grouped in 8 tracking stations

~40 cm

  • A-A collisions  Silicon PIXEL detectors

  • high occupancy  high granularity and radiation hardness

  • tracking planes 10 four-chip planes and 3 sixteen-chip planes

  • ALICE1LHCB chips,pixel size (50  425) mm2

~32 cm

Hitmap (Pb-Pb collision)

Y (cm)

X (cm)

Vertex spectrometer placed in magnetic field  accurate measurement of angle and momentum of tracks at the vertex, covering muon spectrometer angular acceptance

 Expected mass resolution: 20 MeV at w peak

C. Oppedisano


Intermediate mass region excess l.jpg

Intermediate mass region excess

With enhanced charm

p-A collisions

 data described by Drell-Yan + charm decays

S-U and Pb-Pb collisions

 dimuon yield exceeds the superposition of

expected sources

IMR dimuon yields can be reproduced by:

adding thermal radiation to Drell-Yan and open

charm

OR

scaling up of charm contribution vs. centrality

by up to a factor 3

NA60

separate open charm from thermal contribution

Peripheral

collisions

With expected charm yield

M(GeV)

dN/dM

Central

collisions

C. Oppedisano


Open charm tagging l.jpg

Open charm tagging

µ

Muon filter

vertex

, Kµ

offset

<1mm

~10 cm

Dµ

Offset distribution

Background

prompt dimuons

dN/dM

dN/dM

Background

PROMPT

CHARM

open charm

Charm

Prompt

0 100 200 300 400 500 600 700

Offset (mm)

M(GeV)

M(GeV)

  • measure impact parameter of muon tracks

  •  separation of the two main contributions to IMR dimuon spectra:

  • prompt dimuon sample from interaction vertex

  • muon pairs from D decays with offset w.r.t. interaction point

C. Oppedisano


Charmonium production l.jpg

Charmonium production

CHARMONIUM SUPPRESSION

NA50 J/y suppression  indication for onset of deconfinement

NA60

better mass resolution yI and J/y clearly separated

In-In collisions  identification of the physics variable with

threshold behavior

D production is the best reference for J/yproduction study

cc melting

A-DEPENDENCE OF cc PRODUCTION IN p-A COLLISIONS

Around 30-40% of J/y comes from cc radiative decays

NA50  cc anomalously suppressed in semi-central Pb-Pb collisions

NA60

normal absorption pattern of cc

measuring the cc to J/y ratio from p-Be to p-Pb

E866

p-A 800 GeV

NA50

s(p-A) = s0 Aa

C. Oppedisano


Results from p a data i l.jpg

Results from p-A data (I)

Zvertex distribution

Dimuon mass spectrum from muon spectrometer

Data collected in June 2002

6 targets (1 In, 3 Be, 1 Pb, 1 Be) 2 mm thick

Vertex telescope: 14 strip planes + 1 pixel plane

 Zvertex resolution ~ 900 mm

Muon track matching between vertex telescope and muon spectrometer

Target identified by vertex telescope

Dimuon spectrum for each target

p-Be

sw ~ 25 MeV

sf ~ 30 MeV

Zvertex (cm)

C. Oppedisano


Results from p a data ii l.jpg

Results from p-A data (II)

p-In

p-Pb

Dimuon spectra after muon track matching: In and Pb targets

 dimuon mass resolution: ~ 25 MeV at the wpeak and ~ 30 MeV at the f

 precise A-dependence of the w and f production

(NA50 mass resolution for low masses ~ 90 MeV)

Muon offset study  little statistics to extract charm A-dependence

C. Oppedisano


Results from pb pb data l.jpg

Results from Pb-Pb data

Beam tracker vs. pixel telescope

dN/dZ

Xvertex from beam tracker (cm)

Correlation width ~ 30 mm

Xvertex from telescope (cm)

Zvertex (cm)

Pb-Pb collisions at 20 and 30 A GeV (October 2002)

3 Pb targets: 1.5, 1.0 and 0.5 mm thick

Resolution on interaction vertex determination: σZ ~190 mm σX ~20 mm

Pb targets

Beam tracker sensor

Target boxwindow

C. Oppedisano


Charged particle multiplicity measurement l.jpg

Charged particle multiplicity measurement

Plane 1 - Target 1

Beam trigger

Plane 1 - Target 3

Interaction trigger

midrapidity

midrapidity

ZDC spectrum @ 30 GeV

1

2

3

dN/dh (0.1 h units)

Plane 1

Data corrected for acceptance

Multiplicities evaluated from clusters to access midrapidity

Magnetic field switched off

Geometrical acceptances depend on the considered plane-target set

Centrality measured by ZDC

EZDC<1685 GeV  5% of total geometrical x-section

C. Oppedisano


Corrections l.jpg

Corrections

d rays (Pb+fragments)

Plane 1 - Target 3

(worst case)

dN/dh (0.1 h units)

1

2

3

Correction factor for

re-interaction from MC

Plane 1 - Target 1

dN/dh (0.1 h units)

dN/dh (0.1 h units)

d rays from Pb beam  simulations with GEANT3.21

MC reliability tested with beam-trigger data

Corrections factors calculated for each plane-target set

d rays from fragments  evaluated vs. centrality

Secondaries from re-interactions  evaluated using UrQMD 1.2, leads to correction factors from 1.1 to 1.8

Plane 1

After MC corrections distributions in good agreement

C. Oppedisano


Charged particle distributions l.jpg

Charged particle distributions

Centrality bin hmax (dN/dh)hmax(dN/dh)/(0.5*Npart)

0-5 % 2.1 ± 0.1 172 ± 4 0.98 ± 0.02 (stat.) ± 0.11 (syst.)

5-10%2.1 ± 0.1129 ± 4 0.87 ± 0.03 (stat.) ± 0.10 (syst.)

10-20% 1.9 ± 0.298 ± 4 0.85 ± 0.03 (stat.) ± 0.09 (syst.)

20-35%1.8 ± 0.274 ± 6 0.91 ± 0.07 (stat.) ± 0.10 (syst.)

Fit of dNch/dh distributions at 30 GeV  hmax from data compatible with event generator value

Systematic error ~11%(4% from residual data spread at same h, 9% on d-rays contribution,

3% on re-interaction factors, 5% on pixel plane efficiency)

30 GeV

NA60 Preliminary

(dN/dh)/(0.5 Npart)

dN/dh (0.1 h units)

NA60 Preliminary

Npart

h

C. Oppedisano


Dn ch d h 0 5 n part l.jpg

(dNch/dh)/(0.5*Npart)

 Npart estimated from Glauber fit to EZDC spectrum

 translation from laboratory to CMS frame

Charged particle multiplicity per participant in Pb-Pb collisions for 5% most central events:

30 A GeV  (dNch/dh)/(0.5*Npart) = 0.81 ± 0.02 (stat.) ±0.09 (syst.)

C. Oppedisano


Summary and future perspectives l.jpg

Summary and future perspectives

  • Summary on data collected in 2002

  • p-A collisions:

  •  vertex telescope made of silicon strip (and pixel) planes

  •  dimuon mass resolution: ~25 MeV at the w peak, ~ 30 MeV for the fconfirming expectation from simulations

  • Pb-Pb collisions:

  •  vertex telescope in a partial configuration (only 3 pixel planes)

  •  resolution on coordinates of interaction point:

  • ~190 mm on Zvertex

  • ~ 20 mm on transverse coordinates

  •  measurement of charged particle pseudorapidity densities at 30 A GeV

  • These results confirm the feasibility of the experiment and givegood perspectives for next runs with proton and Indium beams

C. Oppedisano


Na60 collaboration l.jpg

NA60 Collaboration

CERN

Bern

Palaiseau

Riken

BNL

Yerevan

Stony Brook

Torino

Lisbon

Cagliari

Clermont

Lyon

R. Arnaldi, K. Banicz, K. Borer, J. Buytaert, J. Castor, B. Chaurand, W. Chen, B. Cheynis,C. Cicalò, A. Colla, P. Cortese, A. David, A. de Falco, N. de Marco, A. Devaux, A. Devismes,A. Drees, L. Ducroux, H. En’yo, A. Ferretti, M. Floris, P. Force, A. Grigorian, J.Y. Grossiord,N. Guettet, A. Guichard, H. Gulkanian, J. Heuser, M. Keil, L. Kluberg, Z. Li, C. Lourenço,J. Lozano, F. Manso, A. Masoni, A. Neves, H. Ohnishi, C. Oppedisano, G. Puddu,

E. Radermacher, P. Rosinský, E. Scomparin, J. Seixas, S. Serci, R. Shahoyan, E. Siddi, P. Sonderegger, G. Usai, H. Vardanyan and H. Wöhri

50 people, 12 institutes, 7 countries

C. Oppedisano


  • Login