1 villars 2004 a future fixed target programme at cern? conclusions of the spsc villars meeting 22...

1

Villars 2004

A Future Fixed Target Programme at CERN?

Conclusions of the SPSC Villars Meeting

22nd-28th September 2004

Ian C. BrockUniversity of Bonn

18/04/23 Ian C. BrockFuture CERN Fixed Target Programme?

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

Outline


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“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 importantrealistic (beams + resources)

short, intermediate, and long term From the Scientific Policy Committee

Charge

SPSC not in approval/rejection mode !


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“… 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 Kπ atoms CNGS

September: Villars December: report to RB + SPC

Input and Timetable

committed beyond 2005}


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Programme Date Morning Afternoon

Wednesday Sept 22 CERN perspective +

acceleratorsMMWSPL

HIF Heavy Ion

1

Thursday Sept 23 Heavy Ion 2 Neutrino 1

Friday Sept 24 Neutrino 2Soft and hard hadron

physics 1

Saturday Sept 25Soft and hard hadron

physics 2 Antiproton 1

Sunday Sept 26 Antiproton 2 HF 1

Monday Sept 27 HF 2Other

Topics Discussion

Tuesday Sept 28Summary, Discussion

& Conclusions

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Machines and Beams


7

CERN 2004


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Users View of Future: pre Villars04

USER

CERN COMMITMENT*

USERS’ WISHES

Short term(low cost)

Medium term(intermediate cost ~asap)

Long term(high cost: >2013)

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 A ** Upgrade ~ 5

Future beams > 2 GeV / 4 MW

EURISOL 1-2 GeV / 5 MW

* Reference value for analysis ** 1350 pulses/h – 3.21013 ppp

● as heard by HIP from users


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Beam loss irradiation @ high intensity multi-turn ejection from PS (“island extraction”)

Period 0.6 s 0.9 s ?

> cost > worse PSB flexibility better

Intensity/SPS pulse increase CNGS flux machine impedance (kickers, RF…) ? injection energy ? bunching in the PS ?

Upgrades

only


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Fixed target CNGSFT vs. CNGS performance 2006, 2007, 2010

0

1

2

3

4

5

6

7

8

9

10

0 1 2 3 4 5 6 7 8CNGS protons on target [1019]

FT

sp

ills

[10

5]

2006

2007

2010

FT request 7.2E5 spills/year

CNGS request 4.5E19 protons/yearCNGS request

4.5 1019 pot/year

FT request7.2 105 spills/year

Without changes

Double batch + Linac4

Double batch

●FT + CNGS share SPS cycles

●Impossible to meet FT + CNGS demands


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Scope of Future Optionsinterest for

LHC upgradeNeutrino physics

beyond CNGS

Radio-active ion

beams (EURISOL)

Others

Low energy50 Hz RCS

(~ 400 MeV/2.5 GeV)

ValuableVery interesting for

super-beam + beta-beam

No ?

50 Hz SPL(~ 2 GeV )

ValuableVery interesting for

super-beam + beta-beam

Ideal

Spare fluxÞ possibility

to serve more users

High energy8 Hz RCS

(30-50 GeV)Valuable

Very interesting for neutrino factory

No Valuable

New PS(30-50 GeV)

Valuable No No Valuable

1 TeV LHCinjector

Very interesting for luminosity

upgrade.Essential for LHC

energyx2

No No Valuable

synergy


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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 @ 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

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Antiproton Physics


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AD


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Unique Ac Decelerator


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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: n~30 !

Unique Physics at CERN

--

-

-

CPT matter-antimatter


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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


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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


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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

-


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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

-

-

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Other Projects


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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.

-


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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 CERN’s 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

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Flavour Physics


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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


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Landscape


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“NA48/3”

~80 K+ πνν

2004 Launch GIGATRACKER R&D 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 io

n

NA48/3 COMPASS


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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+ π+vv 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 R&D and detector developments should be supported.


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SPSC Conclusions (2) In a longer term future CERN could aim at

precision measurements in the neutral channels, K0

L π0e+e- and K0L π0vv, 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.


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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 μ+μ- decay. The feasibility of observing or setting a competitive limit for this decay with the proposed experiment still needs to be demonstrated.

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Heavy Ions


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SPbS Panorama

The SP[b]S Panorama

photons

J/ψ

chemistrye+e-

HBT

spectra ● expt @ SPbS + theory QGP


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Chromodynamic Phase Equilibria

● SPS @ phase transition

T

Early universeRHIC, LHC

B

Hadronicmatter

Critical endpoint

Quark-Gluon Plasma (QGP)

Nuclei

Chiral symmetrybroken

Chiral symmetryrestored

BaryonDominated HG

MesonDominated HG

Color superconductor

Neutron stars

QGP

SPS


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Critical Point● theoretical guidance model dependent

Stephanov


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North Area: Heavy Ions >2005After 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 therequired 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).

It should be noted that ion injection via LEIR for fixed targethas not yet been studied in depth. More studies are requiredat the source, Linac3, LEIR, PS and at the SPS.


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Low Mass Dileptons

CERES/NA45

NA60400 GeV

σ

Mee Mµµ

● Excess dileptons – thermal radiation ?


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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.


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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

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.


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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

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Soft and Hard Hadron Physics


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Hadron Physics Energy frontier

Colliders Precision frontier

Colliders + FT Intensity frontier Theoretical symbiosis

Lattice ChPT pQCD

H1 ZEUS - DESY

GSI

BABAR - SLAC

CDF D0 - FNAL


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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

ap

pro

ved

gluons


43

COMPASS ΔG/G●Finding charm

c

cσ(ΔG/G) proposal = 0.142002+3+4

σ(ΔG/G) = 0.24

-

h

hLeading process

h

hGluon radiation (Compton)

h

h

Photon Gluon Fusion (PGF)

●ΔG/G from high pT hadrons pairs


44

DIRAC

“atomic pairs”

“free pairs”

●ππ and Kπ “atoms” - scattering lengths - PT

● data 2001 – 2003 (PS)

● setting up 2006 (PS)

● running 2007/8 (PS)

● planning > 2008 (SPS ?)

● excess at very small

pL and pT

● experimental = theoretical uncertainty @ SPS

≠ Ke decay


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 ΔG/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-τ sector(µ+N τ +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

71±571±5

Early Solar Neutrino Exps.

SNO

SuperK

Soudan II

MACRO

KamLAND

K2K

LSND

ν-oscillations

New KamLAND

Super-KL/E


50

Hierarchy

~sin223

Solar + KamLAND

Super-K


51

CERN LNGS = CNGS


52

CERN LNGS = CNGSCERN Commitment 5 x 4.5 ·1019 protons on target


53

OPERA

Pb

Emulsion layers

1 mm

Plastic base

• for the full detector:2 supermodules31 walls /

supermodule52 x 64 bricks /wall200 000 bricks

56 emulsion films / brick

~2 kTon (Pb) 0.04 kTon

emulsion

9 kt-yr

Δm2=1.2x10-3 eV2 2.7 eventsΔm2=2.4x10-3 eV2 11 eventsΔm2=5.4x10-3 eV2 54 events

● Ready end 2006


54

ICARUS

muon spectrometer≈2 kton Fe B=1.8 T

3m

LAr drift

1.8kT ready end 2007?Statistics and background with 3kTsimilar to OPERA


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Next ?


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≡ T2K


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Strategy High statistics by high intensity beam Tune E at oscillation maximum Sub-GeV beam

Low particle multiplicity suited for Water Cherenkov Good E resolution : dominated by np

Narrow band beam to reduce BG

0.75MW 50GeV-PS

Off-Axis beam Super-Kamiokande


58

Neutr

ino.

PPAP Mar. 25’04

…osc

illati

ons

Imperial College/RALDave Wark

Beta-beam study group

CERN: -beam baseline scenario

PS

Decay

Ring

Decay ring

Brho = 1500 Tm

B = 5 T

Lss = 2500 m

SPSISOL target & Ion source

SPL

Cyclotrons, linac or FFAG

ECR

Rapid cycling synchrotron

Nuclear Physics

MeV 86.1 Average

MeV 937.1 Average

189

1810

63

62

cms

cms

E

eFeNe

E

eLiHe

P. Zucchelli, Phys. Lett. B, 532 (2002) 166-172

Slide from M. Lindroos


59

Neutr

ino.

PPAP Mar. 25’04

…osc

illati

ons

Imperial College/RALDave Wark

Beta-beam study group

CERN to FREJ USG

enev

e

Italy

130km

40kt400kt

CERN

SPL @ CERN2.2GeV, 50Hz, 2.3x1014p/pulse 4MWNow under R&D phase

Megatonne ?


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θ13 CP sensitivity

Towards Neutrino Factory Horizon


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SPL Proposed RoadmapConsistent 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 R&D”).

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)

Task Name

LINAC4

Design ref inment

Construction

Commissioning

Start operation with PSB

SPL

Design ref inment

Construction

Linac4 displacement + commissioning

Start operation as PS Injector

12/31

12/30

2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016

Linac 4 approval SPL

approvalLHC

upgrade

Warning: Compressor ring and detector (8 years) are not quoted Protons from the SPL ready in 2015


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Proton Driver ν● expensive

● likelihood improves

with synergy

● ν beam R&D for new technology

- target- cooling

(MICE)

● νe - β beam

νμ - superbeam

● ν Fact

Mezzetto


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CNGS Proton Budget CERN committed to delivering 5x4.5·1019 p.o.t. to CNGS aimed at

uniquely demonstrating 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 Europe’s particle physics laboratory, CERN should support, participate, and coordinate such technical developments.

We did not discuss CLICCERN has to decide on relative priorities for

CLIC 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 CERN’s existing commitment to the CNGS programme has been met. By that time C2GT’s competitiveness would be doubtful.


67

≤ 2011: Physics vibrant, important, leading SPS p.o.t ? schedule/prioritise/improve

Completion of hadron program essential CNGS window before T2K Hadron production for ν physics ion+ion ≥ 2009 (synergy with LHC) Rare flavour ≥ 2009 (synergy with LHC) Fundamental physics with p atoms (+medical)

Fixed target physics at CERN? (1)

-

increasing p.o.t


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>2011: Physics must be vibrant, important, leading ion+ion ≥ 2009 (synergy with LHC) Rare flavour ≥ 2009 (synergy with LHC) Fundamental physics with p atoms Hadron structure: GPDs

dynamics: low energy, resonance ν physics: evaluation & R&D @ CERN

p-driver superbeam detector global context NF

Fixed target physics at CERN? (2)

All but HI benefit from/require high intensityRCPSB RCPS …

-… if appropriate ?

synergieswith otherscience?SPL?

1 villars 2004 a future fixed target programme at cern? conclusions of the spsc villars meeting 22...

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