A neutrino factory based on a muon storage ring is the ultimate tool for studies of neutrino oscillations, including possibly leptonic CP violation. It is also the first step towards muon colliders. Physics with the high intensity proton driver is already quite attractive. The aim of the studies as defined by the muon steering group (MUG) in agreement with the CERN management is to have a Conceptual Design Report for a European Neutrino Factory Complex ready by about 2006, i.e. the first LHC collisions. This date is chosen to allow sufficient time for the international decision process that should lead to the beginning of construction as soon as LHC financement is completed, around 2010. In this way, by 2007, CERN would have two valid options for the future: CLIC and a Neutrino Factory Complex. A choice between these two options will depend on physics and on the development of other projects such as the next linear collider, neither of which is known today.
A first round of studies has shown that a neutrino factory could probably be built with accessible technologies, and with performances matching the requirements of an exciting physics programme. The cost evaluations are however quite high (US$ 1.9 Billion from the US study) and the techniques envisaged have often never been applied in practice. Many appealing and partially explored options exist for several of the subsystems. It thus appears that a sizeable programme of R&D will be necessary.
This note is organised as follows. The present organizational structure is described first, followed by a review of the activities of the working groups. Finally, the projects under preparation and for which support will be required are described.
present organisationWorking groups activities
Towards the creation of a European collaboration for accelerator R&D
acceleratorProjects in preparation
ECFA physics working groups
R&D experiments
International Muon ionization cooling experimentconclusions
Large Magnetic Detector
Low energy neutrino superbeam
Appendix
1. Ongoing collaborations
Appendix
2 Collaboration structure of the muon international cooling experiment
ORGANIZATIONAL STRUCTURE:
Present organisation:
Muon Steering group (MUG):
Alain Blondel (Geneva, chair),
Friedrich Dydak (CERN-EP)
John Ellis (CERN-TH)
Enrique Fernandez (Barcelona)
Helmut Haseroth (CERN-PS)
Vittorio Palladino (Napoli)
Ken Peach (Rutherford Appleton Laboratory)
Michel Spiro (IN2P3, France)
Paolo Strolin (Napoli)
Working Group conveners:
Friedrich Dydak, Juan Jose Gomez-Cadenas (Neutrino
oscillations),
Gian Giudice, Andries van der Schaaf (Stopped Muons),
Michelangelo Mangano (DIS),
Gerhard Buchalla (Kaon physics),
Patrick Janot (Higgs factory),
Helmut Haseroth (Neutrino Factory Working Group)
Helge Ravn (Target + Horns)
Horst Schonauer (Accelerator and Compressor)
Roland Garoby (SPL, RF)
Alessandra Lombardi (Cooling studies)
Spokespersons of Experimental R&D :
Friedrich Dydak (HARP), Rob Edgecock (MUSCAT)
The composition and role of this group is an integral part of the package that was submitted to ECFA and endorsed by it. The group is well identified and recognized by the CERN management. The chair (Alain Blondel) was also co-opted in MUG’s first meeting in July 1999, and his mandate renewed in the MUG meeting 31 August until the more formal MCOG structure is in place.
The accelerator group has a direct mandate from CERN
and has its own steering committee, to which the MUG chair is frequently
invited. The leader is Helmut Haseroth. R&D for high intensity proton
source and neutrino factory is supported and funded at CERN, as described
in CERN's medium term plan (MTP).
Towards the creation of a collaboration for research and development towards a European Neutrino Factory Complex:
It is now proposed to develop a collaborative effort to undertake the
accelerator R&D programme at the theoretical, engineering and experimental
levels. The first step, as already discussed over the last year at the
initiative of the CERN management, is to assemble a European Muon Concertation
and Oversight Committee. The first task of this committee will be to review
the status of R&D studies and plans and of the more or less formal
collaborations that have already taken place, and to establish a fist set
of basic goals. It is proposed that two persons (one representative and
one surrogate) of the major participating laboratories and funding agencies
be nominated for a first meeting to be still convened this year. An organisational
structure should be discussed and proposed to the relevant authorities.
Representatives of France (IN2P3, CEA), Germany (DESY, GSI), Italy (INFN),
Switzerland (PSI) and UK (PPARC,UK) have been approached.
A summary of existing collaborations is given in appendix 1.
1 The Neutrino Factory Working Group (NFWG) was mandated in spring 1999 by CERN, under the leadership of Helmut Haseroth. This group has issued a status report and working plan last year that is described in NUFACT note 28. The goals and aims of this group is to study the feasibility of a neutrino factory complex at CERN.
The SPL team, led by Roland Garoby. This team has produced recently a conceptual design report, including a costing of this powerful proton machine. This effort involves collaborations in Europe, for instance with IN2P3 and CEA in France and with LNL and INFN in Italy. An agreement is under negotiation with CEA for the construction and installation at CERN of a 4 MeV high intensity proton source.
The accumulator and compressor working group, led by Horst Schonauer. This group is collaborating in particular with Rutherford Lab.
The target and pion collection team led by
Helge Ravn. This group participates in the E951 collaboration in Brookhaven
(USA), where liquid mercury jets have been succesfully exposed to intense
proton bunches. Higher peak intensities should be available at ISOLDE and
the group is preparing tests on this facility. Collaboration with Lausanne
(laboratoire d'hydrodynamique) and Grenoble (laboratoire de champs intenses),
where liquid mercury jets are being tested in high intensity magnetic 20T.
Horn studies are also well started, with a prototype
horn being build and a test laboratory being set-up. High current studies
are planned for the end of 2002 and should be followed by 50 Hz repetition
rate studies.
The muon front end group, led by Alessandra Lombardi, which has designed a collection scheme with low frequency RF systems, matched to the SPL. This group is very active in the area of ionization cooling and in the preparation work towards a muon cooling experiment. A test cavity is being prepared to test the gradient achievable in a 88 MHz cavity fitted with a focusing solenoid. Collaboration with UK, INFN, and others is rapidly growing. (see below for the cooling experiment)
Although this is not as formalised as the ones above, work is taking place on the muon acceleration and storage ring design, thanks to E. Keil and A. Verdier. The INFN Frascati laboratory has recently begun to work on this subject.
The NFWG holds regular meetings (every two weeks about) that experimental particle physicists also attend regularly.
2. Physics Working Groups, are working under the sponsorship of ECFA. The goal and purpose of these working groups is to establish the physics opportunities offered by a European Neutrino Factory Complex. These working groups are :
The low energy muon working group, convened by Gian Giudice and Andries Van der Schaaf. This group has emphasised the great interest of lepton flavor violating processes like rare muon decays or muon conversion. It now needs to work, in conjunction with experts in the field, on the conceptual designs of the possible slow muon targets, beams and experiments. A significant contribution of this group has been to reveal the potential synergy between the availability of a large flux of muons with the improved production of radioactive nuclei that one can expect with the SPL.
The Kaon physics working group, convened by Gerhard Buchalla, studying the interest of high intensity kaon beams. One major issue here is that this requires that the energy of the proton driver be above 15 GeV, or that a substantial fraction of the protons from SPL is accelerated up to this energy or higher.
The high intensity neutrino physics group, convened by Michelangelo Mangano, studying the opportunities in QCD and electroweak physics offered by the huge neutrino fluxes available in the near vicinity of the muon storage ring of a high energy neutrino factory complex.
The Higgs Factory working group convened by Patrick Janot, studying the physics benefits of medium energy muon colliders, generically at center-of-mass energies equal to the Higgs boson(s) masses to take advantage of direct s-channel production of Higgs and of the unique energy resolution and calibration of muon machines. Muon colliders are a step further in difficulty with respect to the neutrino factory, but it is felt important to keep in mind this important possible extension when discussing the designs.
3. R&D experiments that are now taking place:
3b The MUSCAT experiment at TRIUMF(Canada), spokesperson Rob Edgecock, is set to measure the poorly known tails of multiple scattering of muons at low energies. These properties are important for muon ionization cooling. The experiment had a technical run in 2000 and will take data in end 2001 and 2002.
PROJECTS IN PREPARATION
CONCLUSIONS
An ECFA working group on the future of accelerator-based
High Energy Physics in Europe has recently issued the following recommendations
[ECFA/01/213, 6 september 2001].
[...]
4) an improved educational programme in the field
of accelerator physics and increased support for accelerator R&D activity
in European universities, national facilities and CERN;
[...]
5) a co-ordinated collaborative R&D effort to
determine the feasibility and practical design of a neutrino factory based
on a muon storage ring.
[...]
We believe that our programme of projects fits closely
with the ECFA recommendations. As one can see there is a flurry of initiatives
that have been taken and a flurry of initiatives to come. This wide range
of projects of reasonable size is very attractive, both because of the
novelty offered by the R&D itself and for the prospects offered by
working in collaboration towards an exciting programme of experimental
investigations and discoveries.
.
Alain Blondel
APPENDIX 1 Ongoing Collaborations
SPL : INFN Legnaro, CEA Saclay, ITEP Moscow
Recirculator and accumulator: RAL
Target: BNL, EPFL Lausanne, Grenoble
Horns: Uni Crakow, discussions with France
Phase rotation and cooling:
INFN Frascati,
RAL
Mucool collaboration (IIT chicago, Fermilab, BNL, etc.. )
KEK, Uni Osaka
Consortium of European universities (EuNuFact incl Uni.Geneva)
PSI
RLA and Storage ring: Fermilab, INFN frascati
HARP (24 Institutes) Bari University ,
CERN , Dubna JINR , Dortmund University , Ferrara University
, Geneve University , P.N. Lebedev Physical Institute ,
Legnaro /INFN , Louvain-la-Neuve UCL , Milano University/INFN
, Moscow INR , Napoli University/INFN , Oxford University
, Padova University/INFN , Protvino IHEP, Protvino , Paris
VI-VII University , RAL , Roma I University/INFN, Roma Tre
University/INFN , Sheffield University , Sofia Academy
of Sciences , Sofia University , Trieste
University/INFN , Valencia University
MUSCAT (10 Institutes) Birmingham, BNL, CERN, Imperial College London, Oxford University, RAL, Riken, Tohoku, Triumf, UCLA.
International Muon Ionization Cooling Experiment (around 38 Institutes,
see below)
APPENDIX 2 An International Muon Ionization Cooling
Experiment
Letter of Intent, An International Muon Ionization Cooling Experiment
Summary
A neutrino factory based on a muon storage ring is the ultimate tool
for studies of neutrino oscillations, including possibly leptonic CP violation.
It is also the first step towards mu+mu- colliders. Ionisation cooling
of muons constitutes an important ingredient of the performance and cost
of a neutrino factory, but has never been realised in practice. This motivates
a programme of R&D at international level, including an experimental
demonstration. The aims of this muon ionisation cooling experiment are
as follows:
a) to show that one can design, engineer and build a section of cooling
channel capable of giving the desired performance for a neutrino factory;
b) to place it in a muon beam and measure its performance in a variety
of modes of operation and beam conditions.
The concept of a muon ionization cooling experiment has been extensively
studied, and an international collaboration is set-up to realize it. A
section of a cooling channel assembles liquid hydrogen absorbers providing
energy loss, combined with high gradient RF cavities to re-accelerate the
particles, the ensemble being tightly contained in a magnetic channel.
Spectrometers placed before and after the cooling section perform the measurements
of emittance reduction and transmission. It appears feasible to build a
section of cooling channel that reduces the emittance of a muon beam by
5-10%, and to measure this cooling factor with a precision of 10-3.
This letter of intent describes the principle of the measurements,
the experimental set-up, the requirements on beam properties, the expected
schedule and estimated cost of the experiment, and the requirements on
infrastructure. Technical help from the host laboratory is requested in
preparation of a technical proposal, to refine the layout and implantation
of this experimental facility, and to study the safety issues related to
hydrogen absorbers and to the intense magnetic fields.
International Muon Ionization Cooling Experiment
Steering committee:
A. Blondel* (University of Geneva)
H. Haseroth (CERN**)
R. Edgecock (Rutherford Appleton Laboratory)
Y. Kuno (Osaka University)
S. Geer (FNAL)
D. Kaplan (Illinois Institute of Technology)
M. Zisman (Lawrence Berkeley Laboratory)
* convener for one year (June 2001-2002)
Conveners of Technical teams:
a) Concept development and simulations:
Alessandra Lombardi (CERN **)
Panagiotis Spentzouris (FNAL)
Robert B Palmer (BNL)
b) Hydrogen absorbers:
Shigeru Ishimoto (KEK)
Mary-Anne Cummings (Northern Illinois)
c) RF cavities and power sources
Bob Rimmer (LBNL)
Roland Garoby (CERN**)
d) Magnets
Mike Green (LBNL)
Jean-Michel Rey (CEA Saclay)
e) Particle detectors
Vittorio Palladino (INFN Napoli)
Alan Bross (FNAL)
f) Beam lines
Rob Edgecock (RAL)
Claude Petitjean (PSI)
g) RF radiation
Jim Norem (Argonne)
Ed McKigney (IC London)
** pending the review of CERN activities in accelerator R&D which
will
take place in the framework of the LHC cost-to-completion analysis.
So far incomplete and preliminary list of
Participating institutes
INFN: Bari, Milano, Padova, Napoli, Roma I Roma II, Roma
III
LNF Frascati, LNL Legnaro
Rutherford Appleton Laboratory RAL
University of Oxford, Imperial College London
DAPNIA, CEA Saclay
Louvain La Neuve
NESTOR institute, University of Athens, Hellenic Open University
CERN** (H. Haseroth)
** pending the review of CERN activities in accelerator R&D which
will take place in the framework of the LHC cost-to-completion analysis.
University of Geneva, University of Zurich, ETH Zurich
Paul Scherrer Institute PSI
KEK
Osaka University
Argonne National Laboratory
Brookhaven National Laboratory
Fermi National Accelerator Laboratory
Lawrence Berkeley National Laboratory
University of California Los Angeles, University of Mississippi, University
of Indiana,
Princeton University, University of Illinois, Michigan State University,
Northern Illinois University,
Illinois Institute of Technology, …….