IKON7, Instrument clip session, 15-17 September 2014, ESS Headquarters and Medicon Village, Lund, Sweden

A cold neutron beamline forParticle Physics @ ESS

by Camille Theroine

Why study Particle Physics ?

Understand what the

Universe is and its evolution

Example of question:

- What is the nature of the dark matter ? ….

Why study Particle Physics ?

Understand what the

Universe is and its evolution

Two complementary ways:

- The energy frontier: based on measurements of particle interactions in collisions of highest possible energy, aiming to the production of new heavy elementary particles (LHC @ CERN).

Example of question:

- What is the nature of the dark matter ? ….

Why study Particle Physics ?

Understand what the

Universe is and its evolution

Two complementary ways:

- The energy frontier: based on measurements of particle interactions in collisions of highest possible energy, aiming to the production of new heavy elementary particles (LHC @ CERN).

- The precision frontier: look carefully at low-energy processes that can be accurately predicted by the SM. The differences from expectations in such processes would prove the existence (and give information) on the form of new physics.

Example of question:

- What is the nature of the dark matter ? ….

What the Universe is made of ?

- Heavy elements: 0.03%- Neutrinos: 0.3%- Stars: 0.5%- Mainly Hydrogen/Helium

Could explain why the expansion of the Universe is faster and faster

What the Universe is made of ?

new particles

Examples: • Supersymmetry• Left right symmetry

New interactions

Examples: • Scalar interaction• Tensor interaction

Differences from expectations in

the neutron decay

- Heavy elements: 0.03%- Neutrinos: 0.3%- Stars: 0.5%- Mainly Hydrogen/Helium

Could explain why the expansion of the Universe is faster and faster

Standard Model of particle physics (SM)

Precision experiments

Beyond SMNew interactions

High precision frontier physics with a cold neutron beamline @ ESS

Standard Model of particle physics (SM)

Precision experiments

Beyond SMNew interactions

Neutron decay

Correlations coefficients-> aSPECT, PERKEO III, PERC

Neutron lifetime (beam)

Bound beta decay BoB

High precision frontier physics with a cold neutron beamline @ ESS

Standard Model of particle physics (SM)

Precision experiments

Beyond SMNew interactions

Properties of the neutrons

nEDM (beam)

Neutron charge

Neutron decay

Correlations coefficients-> aSPECT, PERKEO III, PERC

Neutron lifetime (beam)

Bound beta decay BoB

High precision frontier physics with a cold neutron beamline @ ESS

Standard Model of particle physics (SM)

Precision experiments

Beyond SMNew interactions

Properties of the neutrons

nEDM (beam)

Neutron charge

Neutron decay

Correlations coefficients-> aSPECT, PERKEO III, PERC

Neutron lifetime (beam)

Bound beta decay BoB

High precision frontier physics with a cold neutron beamline @ ESS

Hadronic parity violation with neutrons

Nucleon nucleon interaction NPDγ

Pulse structure : eliminate or control systematic uncertainty.

Advantages of long-pulsed spallation source

Pulse structure : eliminate or control systematic uncertainty.

• Wavelength info without statistics loss- Separation of neutron velocity dependent systematic effects e.g : Neutron spin rotation in magnetic fields - Wavelength-resolved polarization for free e.g : NPDγ

Advantages of long-pulsed spallation source

Pulse structure : eliminate or control systematic uncertainty.

• Wavelength info without statistics loss- Separation of neutron velocity dependent systematic effects e.g : Neutron spin rotation in magnetic fields - Wavelength-resolved polarization for free e.g : NPDγ

• Spatial localisation of neutron pulse- Beam-related background- Pulsed measurements to investigate spatial dependence of spectrometer response e.g : PERKEO III, PERC

Advantages of long-pulsed spallation source

Pulse structure : eliminate or control systematic uncertainty.

• Wavelength info without statistics loss- Separation of neutron velocity dependent systematic effects e.g : Neutron spin rotation in magnetic fields - Wavelength-resolved polarization for free e.g : NPDγ

• Spatial localisation of neutron pulse- Beam-related background- Pulsed measurements to investigate spatial dependence of spectrometer response e.g : PERKEO III, PERC

• Time localisation of neutron pulse- Increased signal/background ratio- Measurement of spectrometer background between pulses aSPECT

Advantages of long-pulsed spallation source

Note: This is distance to “detector”

Maximum time-averaged flux with wavelength information

Requirements for the cold neutron beamline (1)

1.8…8Å without frame overlap → 45 m

Note: This is distance to “detector”

Maximum time-averaged flux with wavelength information

Requirements for the cold neutron beamline (1)

1.8…8Å without frame overlap → 45 m

1.8…8Å without prompt pulse → 35 m

Note: This is distance to “detector”

Maximum time-averaged flux with wavelength information

Requirements for the cold neutron beamline (1)

Distance

Resolution

PERCaSPECT

nEDMNPDγ

good resolution : no need

need good resolution

Requirements for the cold neutron beamline (2)

Reasonable wavelength resolution (instantaneous bandwidth)

For 35 m beamline:

• Wavelength resolution ~ 0.3 Å

• Distance between beamlines (5°): 3 m→ need slim neighbours

or double port

• Fast neutron background : curved guide

Courtesy T. Soldner

ILL

Guide length

Flux

Requirements for the cold neutron beamline (3)

Distance

Well-pronounced pulse structure

ILL

Guide length

Flux

Requirements for the cold neutron beamline (3)

Distance

Well-pronounced pulse structure

Summary

Strong european groups and projects for cold neutron decay studies.

Summary

Large experimental programme

• PERC (guide)

• PERKEO II (low divergence)• aSPECT (large diverg.) • npd- (target) …

reference experiments for beam line design

Strong european groups and projects for cold neutron decay studies.

Summary

Cold beam line can profit frompulse structure

• Wavelength information for free• Time localisation of pulse• Spatial localisation of pulse

Eliminate or control systematic uncertainty

Large experimental programme

• PERC (guide)

• PERKEO II (low divergence)• aSPECT (large diverg.) • npd- (target) …

reference experiments for beam line design

Strong european groups and projects for cold neutron decay studies.

Summary

Cold beam line can profit frompulse structure

• Wavelength information for free• Time localisation of pulse• Spatial localisation of pulse

Eliminate or control systematic uncertainty

Large experimental programme

• PERC (guide)

• PERKEO II (low divergence)• aSPECT (large diverg.) • npd- (target) …

reference experiments for beam line design

Requirements for the beam line

• Maximum time-averaged flux with wavelength information

• Reasonable wavelength resolution

• Well-pronounced pulse structure

Strong european groups and projects for cold neutron decay studies.

Summary

Beam parallelising extraction for long experiments (PERC, PERKEO II)

Cold beam line can profit frompulse structure

• Wavelength information for free• Time localisation of pulse• Spatial localisation of pulse

Eliminate or control systematic uncertainty

Large experimental programme

• PERC (guide)

• PERKEO II (low divergence)• aSPECT (large diverg.) • npd- (target) …

reference experiments for beam line design

Requirements for the beam line

• Maximum time-averaged flux with wavelength information

• Reasonable wavelength resolution

• Well-pronounced pulse structure

Strong european groups and projects for cold neutron decay studies.

Summary

Beam parallelising extraction for long experiments (PERC, PERKEO II)

Cold beam line can profit frompulse structure

• Wavelength information for free• Time localisation of pulse• Spatial localisation of pulse

Eliminate or control systematic uncertainty

Large experimental programme

• PERC (guide)

• PERKEO II (low divergence)• aSPECT (large diverg.) • npd- (target) …

reference experiments for beam line design

Focusing option for high flux and large divergence experiments(aSPECT, npdγ)

Requirements for the beam line

• Maximum time-averaged flux with wavelength information

• Reasonable wavelength resolution

• Well-pronounced pulse structure

Strong european groups and projects for cold neutron decay studies.

Summary

Beam parallelising extraction for long experiments (PERC, PERKEO II)

Cold beam line can profit frompulse structure

• Wavelength information for free• Time localisation of pulse• Spatial localisation of pulse

Eliminate or control systematic uncertainty

Large experimental programme

• PERC (guide)

• PERKEO II (low divergence)• aSPECT (large diverg.) • npd- (target) …

reference experiments for beam line design

Focusing option for high flux and large divergence experiments(aSPECT, npdγ)

Requirements for the beam line

• Maximum time-averaged flux with wavelength information

• Reasonable wavelength resolution

• Well-pronounced pulse structure

Strong european groups and projects for cold neutron decay studies.

Proposal for the cold neutron beam line for particle physics will be submitted in January 2015.

Thank you !

nEDM @ ESS

*F. Piegsa, Phys. Rev. C 88 (2013) 045502

Could profit from the pulse structure of ESS:- Signal α 1/f- Systematics α f

= Gains in term of systematic studies

50 m

Systematic effects in EDM …

- Variation of B field

- Leakage currents from E field (produce heating)

- VxE effects : main source of systematic error ( B=VxE : change precession frequency)

The VxE effect can be separated from the EDM phase effect using the pulsed structure of a spallation source like the ESS

Source-detectors 75 mNeutrons 6-10 Å (660-400 m/s)Sensitivity: 5 10∙ -28 ecm

Different velocity dependence of signal and systematics – separation for free