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