L’usine a Neutrinos Simone Gilardoni DPNC - Université de Genève CERN - PS/PP Division

What is a neutrino? Beta decay: continuous e - spectrum Pauli: there is a third particle, the Neutrino ( ) p  n + e + + e n  p + e – + e

ENERGY production GeV MeV GeV Sun ( e ) Nuclear power plants ( e ) n  p + e – + e Atmosphere ( e +  ) Conventional beams  +   + +  NuFact  +  e + + e + 

The oscillation Only 50% of predicted solar e detected Lack in atmospheric muonic neutrino flux (Super-K)  oscillation established

oscillations+mass Two family scheme e,  flavor states; 1,  2  mass states; è Oscillation only possible if m 1  m 2 and non zero mixing angle Other oscill. systems: K L K S, B L B S

Oscillations [E]=GeV; [x]=km; [  m 2 ]=eV 2 Source: E Baseline: l Nature: sin 2 2   m 2 =m m 2 2

Three family oscillation Atmospheric Solar

Appearance P( e     wrong sign muons P(     Disappearance 1 - P(     CP/T violation !! P(      ) = P(      ) CP P(      ) = P(      ) T Neutrino physics  +  e + + e +  Oscillation ? ?

Neutrino factory  +  e + + e +  High intensity: /yr –sensitivity for sin  13 –CP violation in leptonic sector Energy: GeV –   E  Events  E 3 Oscillations  2 flavors: e,  Good knowledge of beam: –Flux (for disappearance) –Small divergence (for flux)

NF layout II 4 MW proton beam at 2.2 GeV Hg liquid target Focusing system: Horn or Solenoid

GeV superconducting proton linac High power MW pulsed p/s –If MW p/s Reuse of LEPII cavities (LEP IS NOT DEAD) Single turn  injection in storage ring (2000 m): –proton burst < 6  s  Linac 2.2 ms  Accumulator Needed

Accumulator and Compressor Accumulator –Macrobunch with internal 23 ns structure (44 MHz) MUON BUNCHES KEEP THIS STRUCTURE –Macrobunch Rep. rate: 13.3 ms (75 Hz) Compressor –Microbunch length reduction to from 3.5 ns to 1 ns –Time spread due to Muon decay  1 ns

PDAC time scheme 44 MHz structure 75 Hz

Proposed site Old ISR tunnel, site of accumulator + bunch compressor Radius = 50 m

Target Station Liquid Mercury jet: –L = 26 cm, R = 1 cm Target must stand power –20 % of Energy lost into the target –1 MW in 60 cm 3  speed 20 m/s –vaporized ? Splash 20 m/s radially High Z : pion production Optimum: 2 interaction lengths

Warning …. This is a neutron spallation source, a proton source, an electron source, a gamma source BUT we call “beam” only the pions which will give us “good muons” which means candidates to enter in the storage ring. FORGET ABOUT ALL THE REST

Particles at target Protons ++ -- e-e- e+e+ No Kaons 20% more  + Vs  - P t  + P tot  + GeV/c

The HARP experiment No experimental data to check simulation in this energy range (proton beam 2.2 GeV) Important for  production in atmosphere and errors on atmospheric neutrino fluxes Harp

Università degli Studi e Sezione INFN, Bari, Italy Rutherford Appleton Laboratory, Chilton, Didcot, UK Institut für Physik, Universität Dortmund, Germany Joint Institute for Nuclear Research, JINR Dubna, Russia Università degli Studi e Sezione INFN, Ferrara, Italy CERN, Geneva, Switzerland Section de Physique, Université de Genève, Switzerland Laboratori Nazionali di Legnaro dell' INFN, Legnaro, Italy Institut de Physique Nucléaire, UCL, Louvain-la-Neuve, Belgium Università degli Studi e Sezione INFN, Milano, Italy Institute for Nuclear Research, Moscow, Russia Università "Federico II" e Sezione INFN, Napoli, Italy Nuclear and Astrophysics Laboratory, University of Oxford, UK Università degli Studi e Sezione INFN, Padova, Italy LPNHE, Université de Paris VI et VII, Paris, France Institute for High Energy Physics, Protvino, Russia Università "La Sapienza" e Sezione INFN Roma I, Roma, Italy Università degli Studi e Sezione INFN Roma III, Roma, Italy Dept. of Physics, University of Sheffield, UK Faculty of Physics, St Kliment Ohridski University, Sofia, Bulgaria Università di Trieste e Sezione INFN, Trieste, Italy Univ. de Valencia, Spain HARP experiment PS institutes 108 authors

Solenoid Capture B=20 T  = 15 cm, L=30 cm Focalisation: Tapered field 20 T  1.25 T B(T) cm Magnetic flux conservation Angular momentum conservation

Horn Introduced in  1961 by S. Van der Meer I = Total current R = distance from the horn axis

Horn for NuFact Horiz.+ Vert. Different scale

Horn II Current = 300 kA (CNGS = 150 kA) –To be pulsed at 75 Hz B = B  Max B  3.75 T B  1/R (R = distance from the horn axis) Inner conductor thickness (Al): Max : 16 mm (Twice CNGS) Min : 1.8 mm Target and proton beam parallel to the axis

After the horn  + horn  + target P t distribution P t GeV/c Protons ++ -- Population Muons  - /    Beam pipe  - /    Sign selective

After the horn II xy Spot size (cm) Horn designed to fit the beam in a R = 30 cm beam pipe x (cm) P x (GeV)  + phase space

Time (arb.) Decay channel Energy (GeV) Huge Energy spread –Huge velocity spread –LEP  E /E  –NF  E /E  2 Debunching Beam type –  –E-t correlation Solenoid B=1.8 T, L=30 m  “Life Time”  18 MeV/c Geometry Energy spread reduction needed

Phase rotation (longitudinal phase space) Aim: monochromatic muon bunch Time dependent Force needed Phase rotation with rf: Phase rotation can change shape, not size of  Input rf wave Output EkEk EkEk EkEk EkEk EkEk EkEk

Phase rot. examples 100  E  300 MeV 30 RF cavities: 2 MV/m 44 MHz L = 1 m B = 1.8 T E = 200  50 MeV

Cooling: the problem (transverse phase space) Accelerato Accelerator acceptance R  10 cm, x’  0.5 rad 200 MeV  and  after focalisation Problem:  Beam pipe radius of storage ring P  or x’ and x reduction needed: COOLING

Ionization Cooling : the principle H2H2 rf Liquid H 2 : dE/dx RF restores only P // : E constant Beam sol

2) Focalisation : a) Needed when x’ reduction comparable with multiple scattering b) same rotation center for the spiral motion. (Rematching) Cooling : the channel 1) Cooling I : x’ reduction3) Cooling II : x’ reduction Heating term ‘ H 2 has X 0 = 8.9 m Cooling works best with high x’

Warning about cooling Stochastic cooling is different: –detection of beam imperfection in a position along a ring –correction via a feedback system in another point of the ring –“slow” process compared to  lifetime STOCHASTIC COOLING IS NOT IONISATION COOLING

Cooling cell

Cooling results Results: 5% of the muons in the acceptance phase space density increased 16 times

Acceleration Must be fast –Muon lifetime   = 2.2  GeV   =1 msec 3 steps: –SC Linac up to 2 (3) Gev –Recirculating SC Linac up to 15 GeV –2nd SC recirculator up to 50 GeV Option of staging the Nufact

Storage ring Two straight sections pointing to two detectors Two possible shapes –triangle –bow tie Lattice design for beam divergence x’   beam divergence dominated by   decay   =m  /p  = 2mrad 50 GeV)  25% useful decays per direction

Storage ring II Horizontal plane Vertical plane Triangle Bow-tie

Around Europe... First possible location: Gran Sasso 732 Km Second location: 3500 Km away best Candidates: Hammerfest or Svalbards (Norway) Gran Canaria (Africa)

The world as playground

beam

Signal for a Nufact  +  e + +  + e  + N   + + X  CC  + N   + X  NC e + N  e - + X e CC e + N  e + X e NC IF: e oscillates into   + N   - + X  CC signal “wrong sign  ” Nufact: 50%  50% e (or opposite)

Magnetic Detector sign selective Baseline 3500 Km 732 Km3.5 x x x x x x 10 5  CC e CC  signal

Conclusion NuFact is one of the official CERN projects after LHC with CLIC R&D needed –SPL: Yellow Report –target experiment HARP pion production Test with Hg in B field, energy deposition –cooling experiment

Generic layout of a cooling test expt. Est. order of magnitude: 30m, 30M, 30 MV

What we need Pion production for different material for different proton energies –position in phase space for each particle Energy, position in 3D, momentum in 3D Pion and muon tracking in a specified geometry (with also B field) Interaction with matter Possibility to interface with tracking program (like PATH or ICOOL) All of that you can do in MARS