Physics Opportunities with Future Proton Accelerators

Report to Neutrino IDSJohn Ellis, March 29th 2007

POFPA study group:Blondel, Camilleri, Ceccucci, JE, Lindroos, Mangano, Rolandi

Advisory group to the CERN DG

The High-Energy Frontier @ CERN

• Context for our approach to high-intensity, lower-energy proton accelerators

• Need to maintain, refurbish CERN’s lower-energy accelerators (linac, booster, PS, SPS)

• Ambition to upgrade LHC luminosity by factor ~ 10 around 2015

• Requires upgrade of proton injector chain

• Look for possible synergies with other physics

European Strategy for Particle Physics

• Highest priority is to fully exploit the potential of the LHC: nominal performance and possible luminosity upgrade (SLHC) ~ 2015

• R&D on CLIC, high-field magnets, high-intensity neutrino facility

• Participation in ILC R&D, decide ~ 2010 (?)• Prepare for neutrino facility decision ~ 2012• Non-accelerator physics• Flavour and precision low-energy physics• Interface with nuclear physics, fixed-target

experiments

Topics for

today

Possible LHC Upgrade Options

• Upgrade of Linac– More intense beam @ 160 MeV: Linac4?

• Superconducting Proton Linac– Up to few MW @ few GeV: SPL?

• Replace PS– New medium-energy injector: PS2?

• Replace SPS– By SC machine @ 1 TeV: SPS+?

• New LHC insertions:– Luminosity 1035 cm-2s-1

PSB SPL’RCPSB

SPSSPS+

Linac4

SPL

RCPSPS

LHCDLHC

Out

put

ener

gy

160 MeV

1.4 GeV4 - 5 GeV

26 GeV40 – 60 GeV

450 GeV

1 TeV

7 TeV

~ 14 TeV

Linac250 MeV

DL

One Possible Scenario for Proton Injectors

PS2

L1, L2SL, DLB, Fk, , NP

SL, DLB, Fk, , NP

SL, DLB,Fk,

L1, L2SL, DLB,k,

SL, DLBk,

L1, L2SL, DL

L1

L1, L2SL, DLBk,

L1, L2

SL

SPL’: RCPSB injector(0.16 to 0.4-1 GeV)

RCPSB: Rapid Cycling PSB(0.4-1 to 5 GeV)

RCPS: Rapid Cycling PS(5 to 50 GeV)

PS2: High Energy PS(5 to 50 GeV)

SPS+: Superconducting SPS(50 to1000 GeV)

SL, DLBFk, NP

Proton flux / Beam power

L1, L2

Ultimate beam from SPS

PSB & PS replaced

SL ++

DL ++

B +++ (>100)

F +++ (~5 GeV prod. beam)

k, x00 kW beam at 50 GeV

NP +++

Layout of the new LHC Injectors

SPS

PS2

SPL

Linac4PS

New Physics @ SLHC

Measure triple-Higgs-boson

coupling with accuracy

comparable to 0.5 TeV LC

Measure triple-gauge-boson

coupling with accuracy

comparable to radiative corrections

Examples of Searches for New Physics

Extended reach for supersymmetry and a Z’ boson

SLHC Physics Reach Compared

Additional LHC Remarks• Reducing β* and minimizing the downtime are both

desirable.• The interaction regions for the SLHC have yet to be

defined– Need significant R&D for focusing magnets, etc.

– Layout may have significant implications for the experiments

• Bunch spacing 25 or 50ns?– 25ns would require machine elements @ 3m from IP

• Shorter spacings have problems with heating of beam pipe• Choice would have implications for injector chain• Final choice of upgrade scenario will require global

optimization of accelerator and detector expenses

Upgrade Scenarios Currently Favoured

- Avoid problems with beam heating

- Peak luminosity ~ 1035 cm-2s-1

Detector Issues for the SLHCHigh radiation in central tracker

Congested layout in forward direction:

space for new low-β* machine elements?

Final SLHC Remarks

• Definition of preferred LHC upgrade scenario in 2010 will require some inputs from initial LHC operations– E.g., neutron fluence, radiation damage and detector

performance, as well as the early luminosity experience and physics results.

• Discussion of many possible scenarios for upgrading the LHC injector complex: Linac4 → SPS+

• Common element in all LHC luminosity upgrade scenarios is Linac4: on critical path for optimizing the integrated LHC luminosity

• Roles for PS2, low-power SPL

The High-Intensity Frontier

• Exploration and understandingNovel phenomenaRare processesHigh statistics

• Active option in front-line physics: factories forZ, B, τ/Charm, K, antiproton, anti-Hydrogen

• Proton driver new opportunities for ν, muon, kaon, heavy-ion, nuclear physics

Neutrino Oscillation Physics

• Programme of precision neutrino oscillation physics, leading to discovery of CP violation, is an important, exciting, high-level goal

• If sin2θ13 > 10-2, may be possible to measure δ using superbeam/β beam + megaton water Cerenkov detector

• Neutrino factory with one or two distant detectors at very long baselines may be needed to measure δ if sin2θ13 < 10-3

• Analysis is one goal of International Scoping Study

ν Oscillation Facilities @ CERN

• CNGS:ν beam from SPS: τ production

• Superbeam?intense ν beam from SPL

• β beam?signed electron (anti) ν beams from heavy ions

• ν factory?muon and electron (anti) ν beams from μ decay

CERN Neutrino Beam to Gran Sasso

GeV 20E í ≈

Optimized for τ detectionCivil works completedCommissioned in 2006Physics in 2007?Intensity upgrade under study

Fluxes from Different ν Facilities

Superbeam

J-PARC

β beam

ν factory

NuMI

How to measure δ ? Error in δ as

function of θ13

SPL + β-beam sufficient if θ13 large,

need ν factory if θ13 small How soon will we know size of θ13?

Key information from Double-Chooz/T2K

Neutrinos as Probes of Standard Model

• Enormous interaction rates in nearby detector• Extraction of αs, sin2 ϑW

• Quark and antiquark densitiesPolarized and unpolarizede.g., strange quarks

• Charm production• Polarization of Λ baryons

also probe of strange polarization

Potential Accuracy for sin2θW

Measuring Strange Partons

Strange + antistrange Strange - antistrange

Muon Physics

• Proton source produces many muons• Rare μ decays

μ e γ, μ eee, μ A e A

Expected in susy seesaw model: probe unknown parameters

• Dipole moments:gμ – 2, electric dipole moment, CPT tests

• Nuclear, condensed-matter physics:(radioactive) μ-ic atoms, muonium, μ-ic

Hydrogen

μ eγ in Supersymmetric Seesaw

Many models predict μ eγ

close to present experimental limit,e.g., model where sneutrino responsible

for inflation, baryogenesis

Measuring SUSY Seesaw Parameters

9 measurable in ν physicsmi, θij, Majorana phases

18 parameters in total

12 Generate baryon asymmetry? 16 measurable in μ, τ decays, …

Comparing μ → eγ and μ → 3e μ → eγ above

experimental limit for generic parameter values

μ → 3e also suppressed for these parameter choices

μ → eγ suppressed for some parameter choices

μ → 3e: T-violating asymmetry AT

Enhanced when μ → eγ suppressed: interference between γ exchange and other diagrams

→ CP, T violation observable

Anomalous Magnetic Moment

‘Consensus’ on discrepancy withStandard Model, based on e+e- data

‘Natural’ supersymmetricinterpretation

Deserves a follow-up experiment

K → πνν: Searches beyond Standard Model

P-326 proposal for K+ → π+νν @ CERN

aims at 80 events -

could reach 1000 events with 4 MW @ 50 GeV

Potential impacts of K → πνν

measurements @ CERN

Isotope Source for Nuclear Physics

• The limits of nuclear existence:neutron & proton drip lines, superheavy elements, extreme nucleonic matter

• Nuclear astrophysics:rp-process, r-process

• Probes of Standard Model:CKM, P, T, CP

• Materials science:radioactive spies, curing chemical blindness,positron annihilation studies, applications to biomedicine, etc.

Physics withRadioactiveNuclearBeams

Extremenuclei

Astrophysics

Particlephysics

Possible EURISOL Site @ CERN

• We consider experimentation at the high-energy frontier to be the top priority in choosing a strategy for upgrading CERN's proton accelerator complex. This experimentation includes the upgrade to optimize the useful LHC luminosity integrated over the lifetime of the accelerator, through both a consolidation of the LHC injector chain and a possible luminosity upgrade project we term the SLHC

• The absolute and relative priorities of these and high-energy linear-collider options will depend, in particular, on the results from initial LHC runs, which should become available around 2010

POFPA dixit …

Blondel et al: hep-ph/0609102

POFPA dixit … redux

• We consider providing Europe with a forefront neutrino oscillation facility to be the next priority for CERN’s proton accelerator complex, with the principal physics objective of observing CP or T violation in the lepton sector

• The most cost-effective way to do this – either a combination of superbeam and -beam or a neutrino factory using stored muons … will depend, in particular, on the advances to be made in neutrino oscillation studies over the next few years. … R&D is needed on a range of different detector technologies suited for different neutrino sources

Blondel et al: hep-ph/0609102

POFPA dixit … redux2

• Continuing research on topics such as kaon physics, fixed-target physics with heavy ions, muon physics, other fixed-target physics and nuclear physics offers a cost-effective supplementary physics programme that would optimize the exploitation of CERN’s proton accelerators. …

• However, we consider that these topics should not define the proton accelerator upgrade scenario, but rather adapt to whichever might be preferred on the basis of the first two priorities.

Blondel et al: hep-ph/0609102

PAF dixit: Benefits for Physics