Villars 2004

1
Villars 2004

• A Future Fixed Target Programme at
  CERN?Conclusions of the SPSC Villars Meeting
• 22nd-28th September 2004
• Ian C. Brock
• University of Bonn

2
Outline

• Framework
• Machines and Beams
• Antiproton Physics
• Other Topics
• Flavour Physics
• Heavy Ions
• Soft and Hard Protons
• Neutrinos

3
Charge

• to review present and future activities and
  opportunities in fixed-target physics, and to
  consider possibilities and options for a future
  fixed target programme at CERN
• globally important
• realistic (beams resources)
• short, intermediate, and long term
• From the Scientific Policy Committee

SPSC not in approval/rejection mode !
4
Input and Timetable

• groups working on fixed target experiments at
  CERN, and also groups which have in mind the
  submission of proposals for such experiments, to
  forward to the SPSC secretariat in due time a
  short report indicating their ideas and plans for
  the future
• SPSC67 April 2004
• 11 submissions received
• COMPASS
• DIRAC Kp atoms
• CNGS
• September Villars
• December report to RB SPC

committed beyond 2005
5
Programme
Date Morning Afternoon Afternoon
Wednesday Sept 22 CERN perspective accelerators MMWSPL HIF Heavy Ion 1
Thursday Sept 23 Heavy Ion 2 Neutrino 1 Neutrino 1
Friday Sept 24 Neutrino 2 Soft and hard hadron physics 1 Soft and hard hadron physics 1
Saturday Sept 25 Soft and hard hadron physics 2 Antiproton 1 Antiproton 1
Sunday Sept 26 Antiproton 2 HF 1 HF 1
Monday Sept 27 HF 2 Other Topics Discussion
Tuesday Sept 28 Summary, Discussion Conclusions


1 including presentations by convenors of
conclusions concerning physics directions
6
Machines and Beams
7
CERN 2004
8
Users View of Future pre Villars04
? as heard by HIP from users
USER CERN COMMITMENT USERS WISHES USERS WISHES
USER Short term (low cost) Medium term (intermediate cost asap) Long term (high cost gt2013)
LHC Planned beams Ultimate luminosity Luminosity upgrades
FT (COMPASS) 7.2105 spills/y ? 7.2105 spills/y
CNGS 4.51019 p/year Upgrade 2
ISOLDE 1.92 mA Upgrade 5
Future n beams gt 2 GeV / 4 MW
EURISOL 1-2 GeV / 5 MW
Reference value for analysis
1350 pulses/h 3.21013 ppp
9
Upgrades

• Beam loss irradiation _at_ high intensity
• multi-turn ejection from PS (island extraction)
• Period 0.6 s ? 0.9
  s ?
• gt cost gt
• worse PSB flexibility better
• Intensity/SPS pulse ? increase CNGS flux
• machine impedance (kickers, RF) ?
• injection energy ?
• bunching in the PS ?

only
10
Fixed target ? CNGS
?FT CNGS share SPS cycles
CNGS request 4.5 1019 pot/year
FT request 7.2 105 spills/year
Without changes
Double batch Linac4
J
J
Double batch
?Impossible to meet FT CNGS demands
11
Scope of Future Options
interest for interest for interest for interest for
LHC upgrade Neutrino physics beyond CNGS Radio-active ion beams (EURISOL) Others
Low energy 50 Hz RCS ( 400 MeV/2.5 GeV) Valuable Very interesting for super-beam beta-beam No ?
50 Hz SPL ( 2 GeV ) Valuable Very interesting for super-beam beta-beam Ideal Spare flux Þ possibility to serve more users
High energy 8 Hz RCS (30-50 GeV) Valuable Very interesting for neutrino factory No Valuable
New PS (30-50 GeV) Valuable No No Valuable
1 TeV LHC injector Very interesting for luminosity upgrade. Essential for LHC energyx2 No No Valuable
synergy
12
Strategy (and action)

• Start 2004/5
• PS multi-turn ejection
• Increase SPS intensity (impacts all machines)
• 0.9s PSB repetition
• Linac 4 design
• ? construction decision _at_ end 2006
• Prepare decision on optimum future accelerator
• Study of a Superconducting Proton Linac (SPL)
• Alternative scenarios for the LHC upgrade
• Context for SPSC strategy and input

13
Antiproton Physics
14
AD
15
Unique Ac Decelerator
16
Unique Physics at CERN

• ASACUSA, ATRAP, ATHENA
• routine production of H
• antiprotonic He p e - ?
• Deceleration and capture of p
• Production of H and He
• yield !
• Spectroscopy ideally 1S 2S
• Present quantum states n30 !

-
-
-
-
CPT matter-antimatter
17
Improvements ATRAP

• Status 4.2K antiprotons are routinely
  accumulated
• Cooling through matter
• Improvements?
• Needed much lower temperatures
• Desired more antiprotons to speed data
  accumulation
• Desired more antiprotons to improve
  spectroscopy
• signal-to-noise
• Decelerator? RFQD? ELENA?
• Would give the much larger antiproton rate
  desired
• Small ring would fit in AD hall
• New beam lines would be needed
• Magnetic fields from experimental apparatus
• Substantial cost

? New experiments AEGIS ALPHA coming
18
ELENA

• A small machine for deceleration and cooling of
  antiprotons after AD to lower energies around 100
  keV is feasible
• One to two orders of magnitude more antiprotons
  can be available for physics.
• Main challenges for the low energy decelerator
  like ultra low vacuum, beam diagnostics and
  effective electron cooling can be solved, using
  experience of AD and member-state laboratories
  where similar low energy ion machines are
  operational (ASTRID, Aarhus CRYring, Stockholm).
  
• The machine can be located inside of the AD Hall
  with only minor modifications and reshuffling of
  the present installation.
• Machine assembling and commissioning can be done
  without disturbing current AD operation

19
SPSC Conclusions (1)

• Opportunity for fundamental physics in the CPT
  violation sector using cold antiprotons
• CERN is the only place in the world to explore it
  and has attracted many external users
• Important scientific and technological milestones
  have been achieved
• routine production of H
• anti-protonic He spectroscopy
• Strong recommendation to continue the AD program
  after 2005 and to implement an improved beam
  switching between experiments
• Installation of the additional deceleration ring
  ELENA would greatly increase the effectiveness of
  current experiments and offer a long term program
  using very cold intense anti proton beams

-
20
SPSC Conclusions (2)

• Different potential signals of CPT violation
  should be explored
• A variety of approaches to trap ground state H
  should continue to be pursued without
  compromising the effective use of available
  resources
• Synergy between the different experiments is
  strongly encouraged
• A roadmap should be available in each
  collaboration describing the medium and long term
  future (with and without ELENA) towards the
  important goal of H spectroscopy

-
-
21
Other Projects
22
SPSC Conclusions (1)

• Axions (CAST)
• The Collaboration has produced the best limits
  to date on the production of axions. It is
  interesting to note that an important and
  substantial enhancement in sensitivity can be
  achieved in the future by taking data with a 4He
  and 3He gas fill. There are also interesting new
  possibilities for developing further the
  experimental techniques at CERN, in particular
  associated with new developments concerned with
  production of axions where a laser experiment is
  claiming unexpected results. The SPSC encourages
  the collaboration to continue to develop its
  ideas and its methods.
• AD4 p therapy
• The work continues to develop its understanding
  of the details of the radiation damage of
  biological matter. In particular the techniques
  concerned with dosimetry and monitoring which are
  used continue to be improved. The SPSC notes that
  in the future the scope of the project could mean
  that increased resources are necessary from CERN.

-
23
SPSC Conclusions (2)

• Electrodynamics in Critical Crystalline Fields
• An interesting new proposal for a measurement of
  trident production in a critical field was
  presented. It was not clear to the SPSC quite how
  the proposed measurement would contribute to the
  understanding and exploitation of such physics in
  the context of CERNs scientific programme.
• (g-2)µ
• The SPSC considers that precision measurements of
  (g-2)µ continue to be an important part of
  understanding physics at the energy frontier.
  Since the completion of the last (g-2)µ
  experiment at BNL, which itself followed the
  pioneering experiment at CERN, it is not yet
  possible to foresee a new European initiative in
  the immediate future. However, the SPSC notes
  that the development of a major new programme of
  muon and neutrino physics at CERN will make major
  new opportunities possible.

Present CERN resource level appropriate
24
Flavour Physics
25
Flavour Physics (Kaon Physics)

• ?Precision measurements of rare flavour decays
  probe the energy scale, and then flavour
  structure, of new physics
• - no SM tree
• - SM suppression
• - short distance dynamics

FCNC
?Experimental challenge BR 10-10 to 10-11

• ? 10 crucial for
• new LHC physics

26
Landscape
27
NA48/3

• 2004
• Launch GIGATRACKER RD
• Vacuum tests
• Evaluate straw tracker
• Start realistic cost estimation
• Complete analysis of beam-test data
• 2005
• Complete of the above
• Complete specifications
• Submit proposal to SPSC
• 2006-2008
• Construction, installation and beam-tests
• 2009-2010
• Data taking

p ? ion NA48/3 ? COMPASS
80 K ? p??
28
SPSC Conclusions (1)

• There is a strong physics case for pursuing an
  ambitious programme of kaon physics at CERN,
  exploiting the high-energy proton beams available
  at the SPS for decay-in-flight rare kaon decay
  measurements. Building on its great expertise in
  high-intensity neutral and charged kaon beams and
  on the outstanding physics achievements of the
  NA48, NA48/1 and NA48/2 experiments in the last
  decade, CERN should remain in the future a major
  laboratory for kaon physics at the sensitivity
  frontier.
• The SPSC welcomes the expression of interest for
  a precise measurement of the K ? pvv
  transition. According to present studies the
  proposed experiment appears competitive in the
  context of the worldwide kaon physics program.
  The goal is to detect more than 100 signal events
  over two years starting in 2009. A major upgrade
  of the present NA48/2 setup is necessary and the
  needed RD and detector developments should be
  supported.

29
SPSC Conclusions (2)

• In a longer term future CERN could aim at
  precision measurements in the neutral channels,
  K0L ? p0ee- and K0L ? p0vv, which by then may
  have been observed elsewhere.
• The SPSC takes note of the extended, compelling
  and competitive kaon program that could be made
  possible by a new high-intensity (MMW)
  high-energy proton machine.

30
SPSC Conclusions (3)

• The NA60 Collaboration has developed over the
  years a high-precision detector, comprising a
  muon spectrometer coupled with a silicon-pixel
  vertex telescope, capable of handling large track
  multiplicities. The SPSC takes note of the
  opportunity of exploiting the excellent di-muon
  mass and vertex position resolution of the NA60
  detector to search for rare open charm decays in
  p-U collisions, including the highly-suppressed
  D0 ? µµ- decay. The feasibility of observing or
  setting a competitive limit for this decay with
  the proposed experiment still needs to be
  demonstrated.

31
Heavy Ions
32
SPbS Panorama

? expt _at_ SPbS theory ? QGP
B. Mueller
33
Chromodynamic Phase Equilibria
? SPS _at_ phase transition
34
Critical Point
? theoretical guidance model dependent
Stephanov
35
North Area Heavy Ions gt2005
After the long shut-down ions will be injected
into the SPS via LEIR. The LEIR project has been
launched for filling the LHC with ions. Filling
the SPS instead will require more resources.
If the ions are required for the SPS fixed target
program and if the required resources are made
available, one might expect to get

• Lead ions from 2009 (after PS-SPS-LHC ions
  running-in)
• Other (lighter) ions depending on LHC ion
  physics program.

It should be noted that many relevant
non-radioactive ion species are possible in
principle, but with significant preparation time
and effort. Note that North Area and LHC ions are
exclusive if not the same ion
Possible intensities are up to 109 Pb54 from
LEIR per transfer (3.6 sec). They can be limited
in LEIR with an interlock based on a BCT
measurement. Limitation of flux in EHN1 requires
new TAX blocks (up to 300 kCHF/beam).
36
Low Mass Dileptons
? Excess dileptons thermal radiation ?
s
400 GeV
NA60
CERES/NA45
Mee
Mµµ
37
Input Elements for SPSC Conclusions

• The CERN fixed target programme with heavy ions
  has, by any measure, been a spectacular success.
  CERN results have contributed to the development
  of theoretical interpretations of the
  measurements in terms of a phase change in
  hadronic matter to quark-gluon, coloured, degrees
  of freedom.
• Recent developments confirm that heavy ion beams
  at the CERN SPS energies and luminosity remain an
  ideal tool to observe the features of the phase
  transition whereas higher energy machines are
  better suited to study the properties of this new
  state of matter.

38

• NA49
• High pT suppression, a potential signature of jet
  quenching in the QGP, is a highlight of the RHIC
  heavy ion results. It has not yet been properly
  addressed at SPS energies.
• In light of this, the NA49 Pb-Pb data should be
  reanalysed. Only then could a proton run for
  reference data be considered. These data would
  clarify the interplay between the Cronin effect
  and high pT suppression.

• NA60
• Steady developments in radiation hard detectors
  have resulted in more refined measurements. In
  particular, recent results from NA60 show the
  improvements that can be made using a pixel
  vertex telescope.
• The p and In data from NA60 should provide
  answers to a set of open questions (open charm,
  rho mass shift, thermal radiation) arising from
  previous experimental CERN results.
• Their requested Pb-Pb data would extend the
  measurements to the highest energy densities
  available at the SPS

39
SPSC General Recommendations

• A major step in the field would certainly be
  achieved through the challenging observation of
  the critical point of the QCD phase transition.
  In addition, QCD lattice calculations are
  expected to constrain better its position in the
  next few years
• Signatures have to be refined and quantified and
  the corresponding experimental signal, or
  signals, have to be understood theoretically. In
  addition, the experimental sensitivity for such
  measurements must be optimised
• The opportunity to pursue a heavy ion physics
  program at the CERN SPS within the framework and
  constraints imposed by the LHC should be
  preserved. Once the LHC has been commissioned
  with ions, an SPS programme aimed at the study of
  rare process signatures and important specific
  issues such as the identification of the critical
  point as well as the study of its properties
  would be possible

40
Soft and Hard Hadron Physics
41
Hadron Physics
H1 ZEUS - DESY

• Energy frontier
• Colliders
• Precision frontier
• Colliders FT
• Intensity frontier
• Theoretical symbiosis
• Lattice
• ChPT
• pQCD

GSI
? CDF D0 - FNAL
? BABAR - SLAC
42
COMPASS

• 1996 Proposal
• 1997 Conditional approval
• 1999 2000 Construction and installation
• 2001 Commissioning run
• 2002 -2004 Data taking µp and µp
• Precision hadron structure
• nucleon spin structure (valence ? sea)
• Precision hadron dynamics
• pQCD ? n-pQCD (Q2, pT2)
• resonant phenomena
• Into the future GPDs and precision structure
  functions

? ?
? ??
approved
gluons
43
COMPASS ?G/G
?Finding charm
c
s(?G/G) proposal 0.14
c
200234 s(?G/G) 0.24
??G/G from high pT hadrons pairs
-
44
DIRAC
?pp and Kp atoms - scattering lengths
- ?PT
? Ke decay
? excess at very small pL and pT
atomic pairs
? data 2001 2003 (PS) ? setting up 2006 (PS) ?
running 2007/8 (PS) ? planning gt 2008 (SPS ?)
free pairs
? experimental theoretical uncertainty _at_ SPS
45
SPSC Conclusions (1)

• The PS/SPS facility is competitive worldwide,
  even with the advent of new machines. It allows
  CERN to have significant impact in the
  understanding of the strong interaction in low
  and high energy domains (Lattice QCD, ChPT and
  pQCD).
• The COMPASS experiment plays an important role in
  the CERN fixed target program with the SPS beam.
  The experiment should complete in the medium term
  their original proposal (especially ?G/G, as well
  as transversity, polarisabilities and hadron
  spectroscopy). The SPSC is concerned about a
  possible shortage of protons, and thus encourages
  the collaboration to prioritise their physics
  program.
• In the longer term, a new programme of
  measurements is proposed. The GPD determinations
  would be in a unique kinematical domain. The
  remaining part of the programme concerns
  structure function measurements using lepton DIS
  and Drell Yan.

46
SPSC Conclusions (2)

• The physics case for the DIRAC experiment,
  including its extension at the PS which has
  already been recommended for approval by the
  SPSC, is important. For the longer term, with
  installation of the existing set-up at the SPS,
  it would be possible to reach a precision
  matching the theoretical predictions.
• The SPSC took note of an Expression of Interest
  to measure lepton flavor violation in the µ-t
  sector(µN ? t N) using the SPS.
• The SPSC is not convinced that the part of the
  conceivedp-A NA49 program related to the
  pentaquark search can lead to a significant
  advance.

47
SPSC Conclusions (3)

• In 2006, until OPERA is ready to take physics
  data with its nominal target mass, it is
  important to take advantage of the opportunity to
  complete as much as possible of the remaining
  approved COMPASS physics programme. To this end,
  it is important that beam delivery starts as
  early as possible in 2006. At the same time, it
  is also important that COMPASS optimise its
  overall physics efficiency. Beyond 2006, the SPSC
  encourages solutions allowing the delivery and
  use of the maximum numbers of protons to satisfy
  the completion of physics experiments using the
  SPS/PS beams.
• In the longer term future, it is interesting to
  note that any high intensity facility at CERN
  will make possible new opportunities for hadron
  physics using neutrino and muon beams.

48
Neutrinos
49
?-oscillations
50
Hierarchy
Solar KamLAND
Super-K
51
CERN ? LNGS CNGS
52
CERN ? LNGS CNGS
CERN Commitment 5 x 4.5 1019 protons on target
53
OPERA
? Ready end 2006
2 kTon (Pb) 0.04 kTon emulsion
56 emulsion films / brick

• for the full detector
• 2 supermodules
• 31 walls / supermodule
• 52 x 64 bricks /wall
• 200 000 bricks

9 kt-yr
?m21.2x10-3 eV2 2.7 events ?m22.4x10-3 eV2 11
events ?m25.4x10-3 eV2 54 events
54
ICARUS
1.8kT ready end 2007? Statistics and background
with 3kT similar to OPERA
LAr drift
n
muon spectrometer 2 kton Fe B1.8 T
3m
55
Next ?
56
T2K
57
Strategy

• High statistics by high intensity n beam
• Tune En at oscillation maximum
• Sub-GeV n beam
• Low particle multiplicity suited for Water
  Cherenkov
• Good En resolution dominated by nm n? m p
• Narrow band beam to reduce BG

0.75MW 50GeV-PS
Off-Axis n beam
Super-Kamiokande
58
Slide from M. Lindroos
59
Megatonne ?
60
Towards Neutrino Factory Horizon
?13
CP sensitivity
61
SPL Proposed Roadmap

• Consistent with the content of a talk by L.
  Maiani at the Celebration of the Discovery of
  the W and Z bosons. Contribution to a document
  to be submitted to the December Council (CERN
  Future Projects and Associated RD).
• Assumptions
• construction of Linac4 in 2007/10 (with
  complementary resources, before end of LHC
  payment)
• construction of SPL in 2008/15 (after end of LHC
  payments)

Linac 4 approval
SPL approval
LHC upgrade
Warning Compressor ring and detector (8 years)
are not quoted Protons from the SPL ready
in 2015
62
Proton Driver ? ?
Mezzetto
? expensive ? likelihood improves with
synergy ? ? beam RD for new technology -
target - cooling (MICE) ? ?e - ß beam ?µ -
superbeam ? ? Fact
63
CNGS Proton Budget

• CERN committed to delivering 5x4.51019 p.o.t. to
  CNGS aimed at uniquely demonstrating t
  appearance. The physics case remains as valid as
  it was at the time of approval, and therefore
  CERN should make every reasonable effort to
  fulfill this commitment. However, no compelling
  scientific case has been offered for CERN to
  increase the scope of this commitment.
• It appears that with the current machine
  performance it is not possible to simultaneously
  satisfy CNGS and COMPASS. We therefore consider
  it very important that efforts continue to
  achieve more available p.o.t., including the
  earliest practicable implementation of multi-turn
  extraction. The experiments should be prepared
  for a longer running period than originally
  planned to achieve their allocation of p.o.t.
• On current schedule the full OPERA detector will
  not be completely ready in early 2006, implying
  that the most efficient use of the available
  p.o.t. will be for the COMPASS programme until
  OPERA is fully constructed later in 2006.
• NEW 60 of ICARUS could be ready at end of 2007

64
CERN participation in the development of future
neutrino facilities

• Future neutrino facilities offer great promise
  for fundamental discoveries (such as CP
  violation) in neutrino physics, and a post-LHC
  construction window may exist for a facility to
  be sited at CERN.
• CERN should arrange a budget and personnel to
  enhance its participation in further developing
  the physics case and the technologies necessary
  for the realization of such facilities. This
  would allow CERN to play a significant role in
  such projects wherever they are sited.
• A high-power proton driver is a main building
  block of future projects, and is therefore
  required.
• A direct superbeam from a 2.2 GeV SPL does not
  appear to be the most attractive option for a
  future CERN neutrino experiment as it does not
  produce a significant advance on T2K.
• We welcome the effort, partly funded by the EU,
  concerned with the conceptual design of a beta
  beam. At the same time CERN should support the
  European neutrino factory initiative in its
  conceptual design.

65
CERN participation in the development of future
neutrino facilities

• Detectors new detector technologies are
  necessary to take full advantage of the physics
  capabilities of future neutrino facilities.
• Examples of needed advances are cheaper, higher
  efficiency, large-area, light sensors and
  magnetized detectors capable of distinguishing
  electrons from positrons.
• Given its central role as Europes particle
  physics laboratory, CERN should support,
  participate, and coordinate such technical
  developments.

We did not discuss CLICCERN has to decide on
relative priorities forCLIC and/or Neutrino
Factory
66
Other Experiments

• Hadron Production
• Further hadron production experiments
  specifically designed to meet the needs of
  neutrino experiments are essential.
• There are several existing CERN detectors which
  could, with some modifications, fulfill this
  requirement. This would be a scientifically
  important and cost-effective use of CERN
  resources.
• C2GT
• This is an interesting idea which would require
  substantial technical development before its
  feasibility could be demonstrated. It also
  requires modifications to the CNGS beamline. No
  such modifications should be made until CERNs
  existing commitment to the CNGS programme has
  been met. By that time C2GTs competitiveness
  would be doubtful.

67
Fixed target physics at CERN? (1)

• 2011 Physics vibrant, important, leading
• SPS p.o.t ?
• schedule/prioritise/improve
• Completion of hadron program essential
• CNGS window before T2K
• Hadron production for ? physics
• ionion 2009 (synergy with LHC)
• Rare flavour 2009 (synergy with LHC)
• Fundamental physics with p atoms (medical)

-
increasing p.o.t
68
Fixed target physics at CERN? (2)

• gt2011 Physics must be vibrant, important,
  leading
• ionion 2009 (synergy with LHC)
• Rare flavour 2009 (synergy with LHC)
• Fundamental physics with p atoms
• Hadron structure GPDs
• dynamics low energy, resonance
• ? physics evaluation RD _at_ CERN
• p-driver ? superbeam ? detector
• global context ? NF

-
if appropriate ?
synergies with other science? SPL?
All but HI benefit from/require high
intensity RCPSB RCPS