Transcript Document 7367043

Physics Opportunities with
Future Proton Accelerators
Report to Neutrino IDS
John 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 lowerenergy 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 (?) Topics
• Prepare for neutrino facility decision ~ 2012
for
• Non-accelerator physics
today
• Flavour and precision low-energy physics
• Interface with nuclear physics, fixed-target
experiments
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
One Possible Scenario for Proton Injectors
Proton flux / Beam power
Linac2
50 MeV
160 MeV
PSB
Output energy
1.4 GeV
4 - 5 GeV
26 GeV
40 – 60 GeV
L1, L2
L1
Linac4
PS
7 TeV
~ 14 TeV
L1, L2
SL, DL
bB,
k, m
SPS
450 GeV
1 TeV
SPL’
RCPSB
L1, L2
SL, DL
L1,
L2
Ultimate beam from SPS
PSB & PS replaced
SL
++
DL
++
bB
+++ (g >100)
nF
+++ (~5 GeV prod. beam)
k, m
x00 kW beam at 50 GeV
NP
+++
LHC
PS2
L1, L2
SL, DL
bB
k, m
L1, L2
SL, DL
bB, nF
k, m, NP
SL, DL
bB, nF
k, m, NP
SPL
RCPS
SPS+
SL
DLHC
SL, DL
bB, nF
k, m
SL, DL
bB
k, m
DL
SL, DL
bB, nF
k, m, NP
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)
Layout of the new LHC Injectors
SPS
PS2
SPL
PS
Linac4
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 SLHC
High 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 understanding
Novel phenomena
Rare processes
High statistics
• Active option in front-line physics: factories for
Z, 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
E ν  20 GeV
Optimized for τ detection
Civil works completed
Commissioned in 2006
Physics in 2007?
Intensity upgrade under study
Fluxes from Different ν Facilities
NuMI
J-PARC
Superbeam
β beam
ν factory
How to measure δ ?
Error in δ as
function of θ13
Key information from Double-Chooz/T2K
SPL + β-beam sufficient if θ13 large,
need ν factory if θ13 small
How soon will we know size of θ13?
Neutrinos as Probes of Standard Model
• Enormous interaction rates in nearby detector
• Extraction of αs, sin2 ϑW
• Quark and antiquark densities
Polarized and unpolarized
e.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,
μAeA
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 physics
mi, 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 → eγ suppressed for
some parameter choices
μ → 3e also suppressed for
these 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 with
Standard Model, based on e+e- data
‘Natural’ supersymmetric
interpretation
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 with
Radioactive
Nuclear
Beams
Particle
physics
Extreme
nuclei
Astrophysics
Possible EURISOL Site @ CERN
POFPA dixit …
• 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 highenergy linear-collider options will depend, in
particular, on the results from initial LHC runs, which
should become available around 2010
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