ivan logashenko for mu2e collaboration workshop on e+e- collisions from phi to psi, sep.19-22, 2011...
TRANSCRIPT
![Page 1: Ivan Logashenko for Mu2e Collaboration Workshop on e+e- collisions from Phi to Psi, Sep.19-22, 2011 Novosibirsk, Russia](https://reader035.vdocuments.mx/reader035/viewer/2022062516/56649e605503460f94b5a8a2/html5/thumbnails/1.jpg)
Ivan Logashenkofor Mu2e Collaboration
Workshop on e+e- collisions from Phi to Psi, Sep.19-22, 2011Novosibirsk, Russia
![Page 2: Ivan Logashenko for Mu2e Collaboration Workshop on e+e- collisions from Phi to Psi, Sep.19-22, 2011 Novosibirsk, Russia](https://reader035.vdocuments.mx/reader035/viewer/2022062516/56649e605503460f94b5a8a2/html5/thumbnails/2.jpg)
Search for cLFVWe had several talks on cLFV already – MEG, COMET, BELLE,…
Why is it interesting?Charged Lepton Flavour Violation in SM is extremely small. Any detectable signal is a sign of New Physics.
Why muons?Copiusly produced
We are trying to measure
Standard Model predicts extremely small value:
( , ) ( , )
( , ) ( , 1)e
A Z e A Z
A Z AR
Z
2* 541
22W,3
3) 10
32Br( k
k ekk
me U
MU
Novosibirsk, 20112 e+e- collisions from Phi to Psi
![Page 3: Ivan Logashenko for Mu2e Collaboration Workshop on e+e- collisions from Phi to Psi, Sep.19-22, 2011 Novosibirsk, Russia](https://reader035.vdocuments.mx/reader035/viewer/2022062516/56649e605503460f94b5a8a2/html5/thumbnails/3.jpg)
History of Mu2eThe current best limit was obtained at SINDRUM II experiment (90’s-2000)
Mu2e is the successor of two earlier proposals:
• MELC at Moscow, early 90’s
The main ideas of the experimental design were proposed
• MECO at Brookhaven, early 2000’s
Part of RSVP program, along with KOPIO, search for K->pinunu
At lof of design work and R&D were performed before the program was terminated
Mu2e goal:
137 10e
Au AuR
Au
e
capture
17 (90% c.l.6 10 )e
e
captu
Al AlR
Al re
Novosibirsk, 20113 e+e- collisions from Phi to Psi
![Page 4: Ivan Logashenko for Mu2e Collaboration Workshop on e+e- collisions from Phi to Psi, Sep.19-22, 2011 Novosibirsk, Russia](https://reader035.vdocuments.mx/reader035/viewer/2022062516/56649e605503460f94b5a8a2/html5/thumbnails/4.jpg)
Mu2e vs MEG
2( 1)CLFV R L
mL e F
k
2(1 ) L L L L L Le u u d dk
k
“Model-independent” lagrangian:
<< 1magnetic moment
type → e rate ~300X
N → eN rate >> 1
four-fermion interation almost no
contribution to → e
μ → eγ decay and μN → eN conversion are complementary
Mu2e
Mu2e @ProjectX
MEG
SINDRUM IIMEGA
Novosibirsk, 20114 e+e- collisions from Phi to Psi
MEG 2011
![Page 5: Ivan Logashenko for Mu2e Collaboration Workshop on e+e- collisions from Phi to Psi, Sep.19-22, 2011 Novosibirsk, Russia](https://reader035.vdocuments.mx/reader035/viewer/2022062516/56649e605503460f94b5a8a2/html5/thumbnails/5.jpg)
Overview of the technique
Stop muons in aluminum
Muons quickly get to 1S orbit
Lifetime of muonic atom is 864 ns
Look for 105 MeV electron
- decay (40%)ee
- capture (60%)XAl
- conversionAl e Al
Hydrogen-like atomBohr radius ≈20 fmNucleus radius ≈4 fm
Most of the background is well below this energy
Use X-rays to monitor number of muons
Novosibirsk, 20115 e+e- collisions from Phi to Psi
![Page 6: Ivan Logashenko for Mu2e Collaboration Workshop on e+e- collisions from Phi to Psi, Sep.19-22, 2011 Novosibirsk, Russia](https://reader035.vdocuments.mx/reader035/viewer/2022062516/56649e605503460f94b5a8a2/html5/thumbnails/6.jpg)
Background: Muon decay-in-orbit (DIO)
Free muon In-orbit
Long tail!
For decay-in-orbit , the maximum energy of electron is equal to the energy of conversion electron (≈105 MeV).
The high-energy tail
Need good energy resolution to beat this background!
5
convE E
eeAl Al
Novosibirsk, 20116 e+e- collisions from Phi to Psi
![Page 7: Ivan Logashenko for Mu2e Collaboration Workshop on e+e- collisions from Phi to Psi, Sep.19-22, 2011 Novosibirsk, Russia](https://reader035.vdocuments.mx/reader035/viewer/2022062516/56649e605503460f94b5a8a2/html5/thumbnails/7.jpg)
Background: Radiative muon capture (RMC)
This background is mostly low energy, but:
Radiative Muon Capture:• with small BR≈10-5, γ’s from muon captures can have high energy up to
• source of high energy electrons, comparable with DIO at the tail: γ can convert in target to e+e- pair, and electron can get almost all energy
• With good energy resolution and proper choice of target (MZ-1>MZ) this source of background is under control
Al(27,13) Mg(27,12) 1.5 0.1 2n p
Muon capture is the source of many background particles:
2.5 MeV (for Al)N convmm E
Novosibirsk, 20117 e+e- collisions from Phi to Psi
![Page 8: Ivan Logashenko for Mu2e Collaboration Workshop on e+e- collisions from Phi to Psi, Sep.19-22, 2011 Novosibirsk, Russia](https://reader035.vdocuments.mx/reader035/viewer/2022062516/56649e605503460f94b5a8a2/html5/thumbnails/8.jpg)
Background: Radiative pion capture (RPC)Muon are produced from pion decays, therefore there are pions in the muon beam.
Radiative Pion Capture:• pions stop at the target and promptly annihilate on the nucleus
• with BR~10-2, γ is produced with energy up to 137 MeV (for Al)
• source of high energy electrons: γ can convert in target to e+e- pair, and electron can enough energy to mimic conversion electron
• This is prompt background, it quickly dies away. Solution: pulsed beam.
(27,13) (27,12)Al Mg
Time distribution of stopped pions in the target
Novosibirsk, 20118 e+e- collisions from Phi to Psi
![Page 9: Ivan Logashenko for Mu2e Collaboration Workshop on e+e- collisions from Phi to Psi, Sep.19-22, 2011 Novosibirsk, Russia](https://reader035.vdocuments.mx/reader035/viewer/2022062516/56649e605503460f94b5a8a2/html5/thumbnails/9.jpg)
Overview of the design
Novosibirsk, 20119 e+e- collisions from Phi to Psi
Production Solenoid 4 m longTransport Solenoid 13 m longDetector Solenoid 12 m long
![Page 10: Ivan Logashenko for Mu2e Collaboration Workshop on e+e- collisions from Phi to Psi, Sep.19-22, 2011 Novosibirsk, Russia](https://reader035.vdocuments.mx/reader035/viewer/2022062516/56649e605503460f94b5a8a2/html5/thumbnails/10.jpg)
Historical perspective: MELC proposal (1992)
Novosibirsk, 201110 e+e- collisions from Phi to Psi
![Page 11: Ivan Logashenko for Mu2e Collaboration Workshop on e+e- collisions from Phi to Psi, Sep.19-22, 2011 Novosibirsk, Russia](https://reader035.vdocuments.mx/reader035/viewer/2022062516/56649e605503460f94b5a8a2/html5/thumbnails/11.jpg)
Production Solenoid
Novosibirsk, 201111 e+e- collisions from Phi to Psi
![Page 12: Ivan Logashenko for Mu2e Collaboration Workshop on e+e- collisions from Phi to Psi, Sep.19-22, 2011 Novosibirsk, Russia](https://reader035.vdocuments.mx/reader035/viewer/2022062516/56649e605503460f94b5a8a2/html5/thumbnails/12.jpg)
Extinction
To avoid prompt background, we use pulsed beamThe signal is extremely rare
Need extinction factor 10-10!…and it has to be measured
Use combination of techniques to achieve this factor
Novosibirsk, 201112 e+e- collisions from Phi to Psi
![Page 13: Ivan Logashenko for Mu2e Collaboration Workshop on e+e- collisions from Phi to Psi, Sep.19-22, 2011 Novosibirsk, Russia](https://reader035.vdocuments.mx/reader035/viewer/2022062516/56649e605503460f94b5a8a2/html5/thumbnails/13.jpg)
Accelerator
Novosibirsk, 201113 e+e- collisions from Phi to Psi
![Page 14: Ivan Logashenko for Mu2e Collaboration Workshop on e+e- collisions from Phi to Psi, Sep.19-22, 2011 Novosibirsk, Russia](https://reader035.vdocuments.mx/reader035/viewer/2022062516/56649e605503460f94b5a8a2/html5/thumbnails/14.jpg)
Mu2e vs NOvA vs g-2
Mu2e can operate concurrently with FNAL neutrino experiments (NOvA)
we use 6 out of 18 Booster batches, which NOvA can’t use during Main Injector cycle
G-2 and Mu2e use the same beam, but in a different mannercannot run concurrently, but there is effort to make it possible to switch between the experiments
Novosibirsk, 201114 e+e- collisions from Phi to Psi
![Page 15: Ivan Logashenko for Mu2e Collaboration Workshop on e+e- collisions from Phi to Psi, Sep.19-22, 2011 Novosibirsk, Russia](https://reader035.vdocuments.mx/reader035/viewer/2022062516/56649e605503460f94b5a8a2/html5/thumbnails/15.jpg)
Muon Beam Line
•Negative gradient
magnetic mirrow
no trapped particles
•Uniform field in tracker region
good resolution
•Torroidal field in the transport solenoid
separation/
Novosibirsk, 201115 e+e- collisions from Phi to Psi
![Page 16: Ivan Logashenko for Mu2e Collaboration Workshop on e+e- collisions from Phi to Psi, Sep.19-22, 2011 Novosibirsk, Russia](https://reader035.vdocuments.mx/reader035/viewer/2022062516/56649e605503460f94b5a8a2/html5/thumbnails/16.jpg)
Transport Solenoid
Novosibirsk, 201116 e+e- collisions from Phi to Psi
![Page 17: Ivan Logashenko for Mu2e Collaboration Workshop on e+e- collisions from Phi to Psi, Sep.19-22, 2011 Novosibirsk, Russia](https://reader035.vdocuments.mx/reader035/viewer/2022062516/56649e605503460f94b5a8a2/html5/thumbnails/17.jpg)
Stopping target
e
17 Al disks, 200 mkm thicknessWhy Aluminum? Perfect for this experiment
•higher Z: larger conversion ratedifferent contributions to the rate
•lower Z: larger lifetimehigher conversion energy
Novosibirsk, 201117 e+e- collisions from Phi to Psi
![Page 18: Ivan Logashenko for Mu2e Collaboration Workshop on e+e- collisions from Phi to Psi, Sep.19-22, 2011 Novosibirsk, Russia](https://reader035.vdocuments.mx/reader035/viewer/2022062516/56649e605503460f94b5a8a2/html5/thumbnails/18.jpg)
T-tracker
18 stations x 12 panels x 2x50 straws =21600 straws
5 mm dia. Mylar straws, 15 μm walls, 20 μm Au-plated W wire
200 μm position resolutionNovosibirsk, 201118 e+e- collisions from Phi to Psi
![Page 19: Ivan Logashenko for Mu2e Collaboration Workshop on e+e- collisions from Phi to Psi, Sep.19-22, 2011 Novosibirsk, Russia](https://reader035.vdocuments.mx/reader035/viewer/2022062516/56649e605503460f94b5a8a2/html5/thumbnails/19.jpg)
Measuring the momentum
Low energy e- pass undetected
For high energy e- we detect several points on the helix
Novosibirsk, 201119 e+e- collisions from Phi to Psi
![Page 20: Ivan Logashenko for Mu2e Collaboration Workshop on e+e- collisions from Phi to Psi, Sep.19-22, 2011 Novosibirsk, Russia](https://reader035.vdocuments.mx/reader035/viewer/2022062516/56649e605503460f94b5a8a2/html5/thumbnails/20.jpg)
CalorimeterLocated downstream of tracker
Main purpose: to provide trigger (1 kHz for E>80 MeV)Provides redundant position, timing and energy data
Possible design:2112 LYSO crystals, 3x3x13 cm3 arranged in 4 vanes. Density 7.3g/cm3, Moliere radius 2.07 cm, Rad. Length 1.14 cm, decay time 40 ns. Light yield relative to NaI 85%.
Two APDs per crystalNovosibirsk, 201120 e+e- collisions from Phi to Psi
![Page 21: Ivan Logashenko for Mu2e Collaboration Workshop on e+e- collisions from Phi to Psi, Sep.19-22, 2011 Novosibirsk, Russia](https://reader035.vdocuments.mx/reader035/viewer/2022062516/56649e605503460f94b5a8a2/html5/thumbnails/21.jpg)
Cosmic Ray Shield
Cosmic rays can generate high energy
electrons
Need high suppression factor – a lot of cosmic ray events over 2 year
running period
Combination of passive (magnetized
iron + dirt) and active (scintillation counters) shielding
99.99% coverage Novosibirsk, 201121 e+e- collisions from Phi to Psi
![Page 22: Ivan Logashenko for Mu2e Collaboration Workshop on e+e- collisions from Phi to Psi, Sep.19-22, 2011 Novosibirsk, Russia](https://reader035.vdocuments.mx/reader035/viewer/2022062516/56649e605503460f94b5a8a2/html5/thumbnails/22.jpg)
Expected sensitivity
Proton flux 1.8x1013 p/s
Running time 2x107 s
Total protons 3.6x1020 p
Stopped μ per proton 0.0025
μ capture probability 0.61
Time window 0.49
Trigger efficiency 0.80
Selection efficiency 0.19
Sensitivity (90% CL) 6x10-17
Events for Rμe=10-16 4
Estimated background 0.18
Novosibirsk, 201122 e+e- collisions from Phi to Psi
![Page 23: Ivan Logashenko for Mu2e Collaboration Workshop on e+e- collisions from Phi to Psi, Sep.19-22, 2011 Novosibirsk, Russia](https://reader035.vdocuments.mx/reader035/viewer/2022062516/56649e605503460f94b5a8a2/html5/thumbnails/23.jpg)
What we expect to see
Novosibirsk, 201123 e+e- collisions from Phi to Psi
![Page 24: Ivan Logashenko for Mu2e Collaboration Workshop on e+e- collisions from Phi to Psi, Sep.19-22, 2011 Novosibirsk, Russia](https://reader035.vdocuments.mx/reader035/viewer/2022062516/56649e605503460f94b5a8a2/html5/thumbnails/24.jpg)
Project schedule
e+e- collisions from Phi to Psi Novosibirsk, 201124
July 2005RSVP @BNL cancelled for financial reasons not related to MECO
October 2007
Mu2e LOI submitted to Fermilab
Fall 2008Proposal submitted to Fermilab and receives Stage I approval
November 2009
CD0 status granted
2010-2011 R&D and design, preparation of CDR2012 CD1
~2013 CD2, Start of Solenoid Construction~2018-2020 Start of data taking
![Page 25: Ivan Logashenko for Mu2e Collaboration Workshop on e+e- collisions from Phi to Psi, Sep.19-22, 2011 Novosibirsk, Russia](https://reader035.vdocuments.mx/reader035/viewer/2022062516/56649e605503460f94b5a8a2/html5/thumbnails/25.jpg)
Project X
There is proposal to replace FNAL’s Booster with new 8 GeV high-intensity linear accelerator, based on ILC technologies – “Project X”
Project X would feed neutrino and rare decay/high precision experiments
Potential to upgrade Mu2e by factor x100!• set much stronger limits (if there is no signal)
• or use different target materials to study nature of new physics (if there is signal)
Serious upgrade of the detector is required
Novosibirsk, 201125 e+e- collisions from Phi to Psi
![Page 26: Ivan Logashenko for Mu2e Collaboration Workshop on e+e- collisions from Phi to Psi, Sep.19-22, 2011 Novosibirsk, Russia](https://reader035.vdocuments.mx/reader035/viewer/2022062516/56649e605503460f94b5a8a2/html5/thumbnails/26.jpg)
ConclusionIn May 2008 P5 (US Particle Physics Project Prioritization Panel) Report stated:
“recommends pursuing the muon-to-electron conversion experiment under all budget scenarios considered by the panel.”
Why?• Mu2e experiment will allow to improve the current limit by 4 orders of magnitude
• if signal is found, it will be an undeniable proof of the New Physics and it will provide data, complementary to LHC
• if no signal is found, it will set constrains much stronger than LHC (up to 1000 TeV mass scale)
• with better muon source and other upgrades, the limits can be improved by another 2 orders of magnitude
Novosibirsk, 201126 e+e- collisions from Phi to Psi