SHiP: Search for Hidden Particles - School of...

9/28/2015 A. Murat GÜLER@METU 1

SHiP: Search for Hidden Particles

A.Murat GÜLER

METU Ankara

METU

IPM school and conference on Particle Physics (IPP15): Neutrino physics, dark matter and B-physics

IPM, Tehran, Iran

22-27 September 2015

On behalf of the SHiP Collaboration

Physics Motivation

Standard Model provided consistent description of Nature’s constituents

and their interactions.

No significant deviation from SM.

But the Standard Model can not explain

Neutrino masses

Dark matter

Baryon asymmetry


Intensity Frontier

Hidden Sector

Fixed Target facility

SHiP

Known Physics

SUSY, Extra dim.,

Composite Higgs

LHC

Energy Frontier

Unknown Physics

Energy Scale

Inte

ract

ion

str

eng

th

SHiP: masses below O(10) GeV

Some yet unknown particles or

interactions would be needed to

explain these puzzles.

The SHiP facility will provide

a unique experimental platform for

physics at the Intensity Frontier.

Physics Motivation

These “hidden sectors" may be accessible to the intensity

frontier experiments via few sufficiently light particles,

which are coupled to the Standard Model sectors via

renormalizable interactions with small dimensionless

coupling constants (“portals ").


Large number of models investigated.

Tau Neutrino Physics.

i) Neutrino portal ii)Scalar portal iii) Vector portal iv)Axion portal

SHiP Collaboration


SHiP is a new proposed fixed-target experiment at the

CERN SPS accelerator to search for hidden, very weakly

interacting new particles.

At the same time, also ideal for ντ physics.

Collaboration 47 institutes from 15 countries, plus CERN

Technical Proposal arXiv:1504.04956


SHiP: a fixed-target facility at the SPS

The SHiP facility is located on

the North Area, and shares the

TT20 transfer line and slow

extraction mode.400 GeV protons from SPS

4x1019 pot/year (~200 days of

running)

Spill = 4x1013 pot per cycle of 7.2 s

with slow beam extraction (1s)

Proposed implementation is based on

minimal modification to the SPS complex

Experimental Requirements


In order to maximize the acceptance: detector is close as possible

to target.

Decay vessel: “vacuum” to avoid ν-interaction (10-6 bar).

Magnetic spectrometer to reconstruct HNL mass.

Signal signature:

Charged tracks forming an isolated

vertex inside the fiducial volume.

Candidate momentum pointing back to

the target.

Many of the hidden particles are expected to be accessible through

the decays of heavy hadrons ⇒High intensity beam dump

experiment in order to maximize the production of K, D, B mesons.

The smallness of the couplings implies that the objects are very

long-lived: Long decay volume.

SHiP beam-line


Initial reduction of beam induced backgrounds- Heavy target to maximize Heavy Flavour production (large A) and minimize neutrinos from

π/K →μν decays (short λint)

- Hadron absorber

- Effective muon shield (without shield: muon rate ~1010 per spill of 4x1013 pot)

- Slow (and uniform) beam extraction ~1s to reduce occupancy in the detector.

The SHiP Detector


made of 2 magnets to

bent out muon beyond the

vacuum vessel (weight≈2800t)

OPERA type neutrino

target in B-field RPC

and drift tubes for muon

measurement

10-6 bar vacuum to

suppress the neutrino

int. Elliptical (5mx10m)

to avoid the large muon

flux.

Spectrometer, ECAL,

HCAL and Muon

detector

Heavy material to

stop K/π

Physics Program


All physics scenario are described in detail in physics proposal.

85 theorists

200 pages

Neutrino Portal


N1 is a dark matter candidate (m≈ O(1) keV).

N2, N3 give masses to neutrinos and produce

baryon asymmetry of the Universe (m≈

O(100) MeV-GeV)

The neutrino Minimal Standard Model

(υMSM):Adds three right-handed, Majorana, Heavy

Neutral Leptons (HNL), N1, N2 and N3

Matter anti-matter asymmetry in the Universe,

neutrino masses and oscillations, non-baryonic

dark matter.

The Scalar and Vector Portals


S production from B, D and K decays

p+target→hX

S decays :S→ee,μμ,ππ, KK

Dark photon (A’) model

γ’ production fromMeson decays

Bremsstrahlung (pp→ppV)

QCD (q+q →V ; q+g →q+V)

γ’ decays:γ’→ee,μμ,ππ

Mixing with SM Higgs with angle Θ vs. ms

SM Higgs+ real singlet scalar

SHiP

Summary of the main decay modes of hidden particles

in various models


SHiP Neutrino Program SHiP setup ideally suited to study neutrino and anti-neutrino

physics for all three active flavours.

High charmed hadrons production rates ⇒ high neutrino fluxes

from their decays, including remnant pion and kaon decays.


Tau Neutrino Physics


Less known particle in the Standard Model

• First observation by DONUT at Fermilab in 2001 Phys. Lett. B504

(2001) 218-224.

const () = (0.390.130.13)10-38 cm2 GeV-1

(K(E) describes the kinematical suppression due to the tau mass )

DONUT ντ Candidate

9 events (with an estimated

background of 1.5) reported in

2008 with looser cuts.

() = const EK(E)

Tau Neutrino Physics

5 candidates reported by OPERA for the discovery (5.1 result) of appearance

in the CNGS neutrino beam (Phys. Rev. Lett. 115, 121802).

Tau anti-neutrino is never observed.

Signal/Background Yield


Main background in υτ and anti-υτ searches is the charm production in

υμCC (anti-υμCC ) and υeCC (anti-υeCC ) interactions, when the primary

lepton is not identified.

Number of υτ and anti-υτ produced in the beam dump.

SIGNAL

EXPECTATION R=S/B RATIOBACKGROUND

F4 and F5 Structure Functions


Through ντ and anti-ντ identification: unique capability of being

sensitive to F4 and F5

F4 = F5 = 0

SM prediction

At LO F4= 0, 2xF5=F2

At NLO F4 ~ 1% at 10 GeVE(ντ) < 38 GeV

r>1.6 evidence for non-zero values of F4 and F5

Charm Physics

Expected charm exceeds the statistics

available in previous experiments by

more than one order of magnitude


In NuTeV ~5100 νµ , ~ 1460 anti-νµ

In CHORUS ~2000 νµ , 32 anti-νµ

No charm candidate from νe and ντ interactions ever reported!

Strange Quark Content

Charmed hadron production in anti-neutrino interactions selects anti-

strange quark in the nucleon.

Strangeness important for precision SM tests and for BSM searches.

W boson production at 14 TeV: 80% via ud and 20% via cs.


Fractional uncertainty of the individual parton

densities f(x;m2W) of NNPDF3.0

Associated Charm Production


CHORUS observed 3 events in NC interactions & 1 event in CC interactions

Only gluon bremsstrahlung

in CC.

Boson-gluon fusion &

Gluon bremsstrahlung in

NC.

About 30 events are expected…

Boson-gluon fusion Gluon bremsstrahlung

SHiP Neutrino Detector


Nuclear Emulsion


Nuclear Emulsion is a special kind photographic film.: AgBr micro crystal semiconductor (Band gap ~ 2.6eV).

Signal is amplified by chemical process (developing).

50 micron

Microscopic Image

Recorded as silver grains

along the line particle passed through

Sub micron resolution 3D tracking

AgBr crystal 0.2-0.3 μm

Emulsion Microscope


Scanning speed/system: 75cm2/h

High speed CCD camera (3 kHz)

Piezo-controlled objective lens

FPGA Hard-coded algorithms

European Scanning System(OPERA)Japanese Scanning System(OPERA)

Scanning speed/system: 20cm2/h

Customized commercial optics and mechanics

asynchronous DAQ software

The Neutrino Target


Target Trackers Provide time stamp

Link track information in emulsion

to signal in TT.

Emulsion Cloud

Chamber (ECC) ECC: a sequence of passive

material plates interleaved with

emulsion films.

Nuclear emulsion provides high

spatial resolution for tau/charm

detection.

Passive material(Lead)10X0

Diopolar Magnet To measure the charge of the

decay products .

Muon Spectrometer Perform the muon

identification and measure

its charge and momentum.

Lepton Flavour Identification Emulsion Cloud Chamber is a standalone detector

– νμ identification: muon reconstruction in the magnetic spectrometer!

– νe identification: electron shower identification in the brick!

– ντ identification: disentanglement of τ production and decay vertices


Tau/anti-tau Separation


TASK

Electric charge and momentum measurement of τ lepton decay products

Key role for the τ→h decay channel

3 OPERA-like emulsion films

2 Rohacell spacers (low density material)

1 Tesla magnetic field

PERFORMANCES

Electric charge determined up to 10 GeV/c.

Momentum estimated from the sagitta.

Δp/p < 20% up to 12 GeV/c

Muon Identification


Muon come fromτ →μ decays

νμ CC interactions

μ identification at primary vertex for

background rejection

12 iron layers

11 RPC layers

6 Drift Tube Trackers Planes

Muon Charge and Momentum Measurement


Opposite magnetization in the two arms two opposite curvatures.

Momentum resolution is better than 25 %.

Charge measurement efficiency is 94 %.

Summary SHiP experiment at CERN is proposed to search for New

Physics in the largely unexplored domain of new, very

weakly interacting particles with mass O(10) GeV.

SHiP will perform a complement searches for new

searches at energy frontier at CERN.

Also unique detector for neutrino physics/charm physics.

Technical and Physics proposal have been submitted to the

SPSC in April 2015.


Back up Slides


ECAL/HCAL


SHiP Collaboration


SHiP Collaboration at the time of TP:

243 members from 45 institutes in 14 countries.

Project Schedule


SHiP Collaboration was formed 2014

Technical Proposal was submitted April 2015

Technical Design Report 2018

Construction-Installation-Comissioning 2018-2023

Data Taking and analysis 2026

Cost


Portals


Strange Quark Content


Improvement achieved on s+/s- versus x

Significant improvement (factor two) with SHIP data

Added to NNPDF3.0 NNLO fit, Nucl. Phys. B849 (2011) 112–143, at Q2 = 2 GeV2

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