Hadro-production measurements for the T2K experiment with the NA61/SHINE detector at the CERN SPS
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Transcript of Hadro-production measurements for the T2K experiment with the NA61/SHINE detector at the CERN SPS
Hadro-production measurements for the T2K experiment with the NA61/SHINE detector at the CERN SPS
Claudia Strabel, ETH ZurichFor the NA61/SHINE Collaboration
WIN‘09 Workshop14.-19.09.09, Perugia
Outline
Physics Goals (T2K)NA61/SHINE Detector
Inelastic X-Section (‘07 Pilot Run) Results (‘07 Pilot Run)
Summary and Outlook
Claudia Strabel, NA61 @ CERN SPS
Grandmother (beam
particle)Mother (secondary
particle)
Search for Critical PointCosmic-Ray Air ShowersPierre Auger + KASCADE
-Beam CharacterizationT2K
A+A collisionsp+C, +C collisions
p+C collisions
NA61/SHINE (SPS Heavy Ion and Neutrino Experiment)
One of the main physics goals of NA61/SHINE:
T2K @ JPARC (Japan):
- Long baseline (295km) neutrino oscillation experiment
- Protons (30-50GeV) + carbon target (90cm) → intense beam
- Neutrino spectra measured off-axis at the near and far detectors: ND280 and SK
3
JPARC
p2.5°SK
295km 280m 0m
ND
p accelerator facility
Precision measurements of hadron production
for the prediction of -fluxes at T2K
Physics Goals (I)
Both analysis rely on the spectra measured at SK and the predicted spectra at SK:
Far to Near (F/N) ratio R: is not constant with respect to E
→ to predict the flux correctly details of parent hadro-production kinematics needed
Main aims of T2K:
o Search for and measurement of the → e appearance
» improved sensitivity to the so far unknown mixing angle 13
o Refinement of disappearance measurements
» improved determination of 23 and m223
Physics Goals (II)
Claudia Strabel, NA61 @ CERN SPS
E [GeV] E [GeV]
Flux(normalized to
SK)
F/N Ratio ()
The goal is to reduce the error on the F/N ratio to a negligible level compared to other
contributions to the systematics (ND280 spectrum measurements, cross-section, efficiencies, etc.),
therefore the aims are:
To reach this precision we need ~200k reconstructed π tracks in p+C interactions at 31GeV/c
Furthermore, and K from secondary interactions in the T2K target needed to be studied
Physics Goals (III)
Simulated distributions of and K whose daughter pass through SK:
Measure K/ ratio with an uncertainty of 10%
Predict Far/Near neutrino flux ratio to 3%
Claudia Strabel, NA61 @ CERN SPS
Analysis Strategies for T2K
Strategy A
- Measure the inclusive p+C cross section with a thin target over a broad kinematical
range and different particles (, K, p)
- Use the measured cross sections as input to the beam MC for generating the primary
interaction. Secondary interactions, however, will be described by hadronization
models (e.g. FLUKA)
- Compare the MC predictions to the /K yields measured off C-targets of different
lengths (e.g. T2K replica target) and adjust the model accordingly
Strategy B
- Measure /K yields off the T2K replica target
- Use measured /K yields as input to the beam MC
(no simulation of secondary interactions required)
Claudia Strabel, NA61 @ CERN SPS
NA61/SHINE – Fixed Target Experiment at CERN SPS
NA49 Setup + Upgrades:
Large acceptance (up to 70%) spectrometer for charged particles
TPCs as main tracking devices
2 dipole magnets with bending power of max 9 Tm over 7 m length (2007-Run: 1.14 Tm)
High momentum resolution: (p)/p 2 ≈ 10-4 (GeV/c)-1
Good particle identification: (ToF-L/R) ≈ 100 ps, (dE/dx)/<dE/dx> ≈ 0.04, (minv) ≈ 5 MeV
New ToF-F to entirely cover T2K acceptance ((ToF-F) ≈ 120 ps, 1<p <3 GeV/c, 50<<150 mrad)
Claudia Strabel, NA61 @ CERN SPS
2009/11He BEAM PIPE
2007/11
PSD
Secondary hadron beam composed of 83.7% +,
14.7% p and 1.6% K+
Proton beam particles identified by CEDAR (C1) and
threshold Cerenkov counters (C2)
Incoming p then selected by several scintillator counters
(S1, S2, V0, V1)
→ beam defined as B = S1•S2•V•C1•C2
Trajectory of beam particles measured by the beam
position detectors (BPD-1/-2/-3)
Interactions in the target selected by anti-coincidence
of the beam particle with a small scintillator S4 (B•S4)
Setup of Beam Line
Claudia Strabel, NA61 @ CERN SPS
Beam DivergenceBeam Spot at BPD3
Triggered Protons (C1•C2)
All Beam Particles
p
p
Thin Carbon Target
T2K Replica Target
Setup of Beam Line – Target
Claudia Strabel, NA61 @ CERN SPS
2 different carbon targets (isotropic graphite, = 1.84 g/cm3):
Thin Carbon Target:
- 2.5 x 2.5 x 2cm3,
- int. length ~0.04
- used to evaluate inclusive x-sections
T2K Replica Target:
- Ø= 2.6cm x 90cm,
- int. length ~1.9
- used to study secondary interactions
Aims of the first NA61 run in October 2007:
- to set up and test the NA61 apparatus and the detector prototypes
- to take pilot physics data for T2K with 30.9 GeV/c protons:
Replica target: ~230k events
Target out: ~80k events
Thin target: ~660k events
Cross Section Normalization
trig thus involves the trigger rate and the target properties
- The real interaction probability (Pint) is calculated as the difference of the rate obtained with
and without target:
: density, L: length
NA: Avogadro const.
A: Atomic number
Leff: effective length
abs: abs. length
trig = 297.5 ± 0.7 ± 3.9 mb
- Interaction rate (Data):
- Target out: (1.72 0.01)%
- Target in: (7.07 0.01)%
- Leff = 1.95 cm High Tout/Tin rate due to
inelastic and elastic interactions in the material
of the beamline
€
ε =RT out
RT in
=24.3%
Claudia Strabel, NA61 @ CERN SPS
The inclusive inelastic cross section of a particle type can experimentally be expressed by n: target properties,
beam: # of incoming beam p,
Ntrig: # of triggers,
trig: trigger cross section,
n: # of identified particles
in a given bin p- bin
11
NA61 Preliminary
→ Preliminary value for the inel is in good agreement with previous measurements
G. Bellettini et al., Nucl. Phys. 79 (1966) 609, S.P. Denisov et. al. Nucl. Phys. B61 (1973) 62, A. Carroll et al., Phys. Lett. B80 (1979) 319
inel can be obtained from the trig by applying the following corrections:
1) Subtract the contribution of elastic interactions due to large angle coherent scattering
2) Add the contribution of lost events where a secondary particle hits S4. Here, the major
contribution comes from quasi-elastic scattering of the incident protons (lossp). Also
secondary pions or kaons hitting S4 have to be taken into account (loss)
→ Corrections have been estimated with Geant4 simulation
Inelastic Cross Section
syst. error
stat. error
Recalculated from
NA61 Preliminary
Particle Identification – Strategy (I)
Energy Loss Measurements
Below p = 1 GeV/c dedicated dE/dx
analysis in 1/2 region
For 1 < p < 4 GeV/c Bethe-Bloch curves
cross each other making particle
identification not reliable
→ additional information from ToF
required
Above p = 4 GeV/c dE/dx analysis
in relativistic rise region
Claudia Strabel, NA61 @ CERN SPS
Particle Identification – Strategy (II)
Combined Energy Loss and
Time-of-Flight Measurements
In 1 < p < 6 GeV/c Time of Flight
measurements
Combined dE/dx and ToF analysis
Claudia Strabel, NA61 @ CERN SPS
K
p
2 < p < 3 GeV/c
3 < p < 4 GeV/c
4 < p < 5 GeV/c
K
p
e
K
p
e
K
p
e
Particle Identification – Strategy (III)
Analysis of Negatively Charged Particles
The analysis of negatively charged hadrons,
h- analysis, from the primary vertex is based on
estimation that more than 90% of produced h-
in p+C collisions ast 31 GeV/c are - mesons
The remaining small fraction includes K- and e-
and negligible number of anti-protons
Venus-GHEISHA and Geant MC simulation is
used to calculate corrections for geometrical
acceptance, reconstruction efficiency, weak
decays and lepton contamination
Finally corrected spectra of - in all momentum
range are obtainedClaudia Strabel, NA61 @ CERN SPS
Results from dE/dx Analysis – + and - below 1GeV/c
Claudia Strabel, NA61 @ CERN SPS
Results from dE/dx and h- Analyses – -
Claudia Strabel, NA61 @ CERN SPSSystematical error below
20%
Results from h- and dE/dx+ToF Analyses – -
Claudia Strabel, NA61 @ CERN SPS
Results from h- Analysis – -
Claudia Strabel, NA61 @ CERN SPS
Summary and Outlook (I)
Claudia Strabel, NA61 @ CERN SPS
NA61/SHINE is a large acceptance hadron spectrometer at the CERN SPS which will
precisely measure the particle production from the interaction of a 30 GeV proton beam
on different Carbon targets
→ Thin target: for the determination of inclusive cross sections
→ T2K replica target: for the study of secondary interactions in the T2K target
During the 2007 pilot run data on proton-Carbon interactions were registered
→ good quality of data, though limited in statistics
→ trig and inel were measured. Preliminary inel is in good agreement with previous
measurements
→ high quality of track reconstruction and particle identification has been achieved
→ the data and detailed simulations confirm that phase space needed for T2K measurements
is covered
→ first preliminary hadron spectra for T2K have been obtained
→ work on T2K replica target data is in progress
Summary and Outlook (II)
Claudia Strabel, NA61 @ CERN SPS
2009 successfully started on July 26th 2009 (3 months of data taking)
→ detector upgrades for this run
– TPC read-out and DAQ → increase of event rate by factor 10 (70 Hz)
– new trigger system
– increased ToF-acceptance (pmin 1 GeV/c → 0.6 GeV/c)
– new Beam Position Detectors of 5 x 5 cm2 to fully cover x-section of the
T2K replica target
→ 3 weeks were dedicated to T2K measurments (p+C at 31 GeV/c)
→ 6M interaction triggers collected for thin Carbon target and 3M triggers for the
T2K replica target
Claudia Strabel, NA61 @ CERN SPS
Long Target Data from 2009
22
121 scientists from 24 institutes and 14 countries
University of Athens, Athens, GreeceUniversity of Bergen, Bergen, NorwayUniversity of Bern, Bern, Switzerland
KFKI IPNP, Budapest, HungaryCape Town University, Cape Town, South Africa
Jagellionian University, Cracow, PolandJoint Institute for Nuclear Research, Dubna, Russia
Fachhochschule Frankfurt, Frankfurt, GermanyUniversity of Frankfurt, Frankfurt, GermanyUniversity of Geneva, Geneva, Switzerland
Forschungszentrum Karlsruhe, Karlsruhe, GermanySwietokrzyska Academy, Kielce, Poland
Institute for Nuclear Research, Moscow, RussiaLPNHE, Universites de Paris VI et VII, Paris, France
Pusan National University, Pusan, Republic of KoreaFaculty of Physics, University of Sofia, Sofia, Bulgaria
St. Petersburg State University, St. Petersburg, RussiaState University of New York, Stony Brook, USA
KEK, Tsukuba, JapanSoltan Institute for Nuclear Studies, Warsaw, Poland
Warsaw University of Technology, Warsaw, PolandUniversity of Warsaw, Warsaw, Poland
Rudjer Boskovic Institute, Zagreb, CroatiaETH Zurich, Zurich, Switzerland
The NA61 Collaboration