trabajo final de grado física(uv): angular distribution and energy spectrum of boosted off-axis...
DESCRIPTION
Thesis of my bachellor in Physics. We analise the angular distribution and the energy spectrum of neutrinos coming from decaying pions in a boosted frame. From this we observe the benefits of placing a detector at an off-axis angle respect to the trajectory of the pion. In concrete we derive the effects of adding first order corrections to the mass of the initially set massless neutrino in the kinematical scheme. We compare the results with the well-known biography and determine that those corrections lead no contribution. Finally we discuss the importance of this scheme on the neutrino experiments nowadays. A higher detection rate leads better results on the actual detections. In a near future this could shed some light on some of the most elusive problems nowadays in neutrino physics. For example, the neutrino mass hierarchy or the CP violation in the leptonic sector. We pay special attention to the recent results of T2K (Tokai to Kamioka) and NOvA.TRANSCRIPT
Angular distribution and enegy spectrum of boostedoff-axis neutrinos
Christian Roca CatalaSupervised by: Jose Bernabeu Alberola
Universidad de Valencia (UV)
July 22, 2013
What is the scope of this presentation?
“I have done a terrible thing, I have postulated a particle that cannot bedetected”Wolfgang Ernst Pauli, 1930
Fortunately he was WRONG and neutrinos can be detected and thus,their oscillations!Christian Roca Catala (UV) Trabajo Fin de Grado July 22, 2013 2 / 42
What is the scope of this presentation?
Question: What are we going to study?
Answer: The project presented today it’s about measuring the neutrinooscillations. The performance of new generation experiments it’s capitalin order to disentangle the open problems in neutrino physics nowadays.
Question: Why we want to measure neutrino oscillations?
Answer: To solve the open problems in the neutrino sector:
Neutrino mass hierarchy: sign(∆m223) → neutrino mass picture
would be completed
CP violation in leptonic sector: asymmetry matter-antimatter inearly universe (leptogenesis)
Christian Roca Catala (UV) Trabajo Fin de Grado July 22, 2013 3 / 42
What is the scope of this presentation?
Question: How we may perform the measurements?
Answer: Using the off-axis method → Improving the energy resolutionof the neutrino beams detected it’s crucial for measuring the neutrino
oscillations parameters.
Question: Who is using this performances?
Answer: Long base-lines accelerator experiments of neutrino appearancelike T2K and NOνA
At the end → new results released 3 days ago by T2K!!
Christian Roca Catala (UV) Trabajo Fin de Grado July 22, 2013 4 / 42
What is the scope of this presentation?
Accelerator Experiments
NOνA (Fermilab)
T2K (Japan)
MINERνA (Fermilab)
Reactor Experiments
Double Chooz (France)
RENO (South Korea)
Daya Bay (China)
Christian Roca Catala (UV) Trabajo Fin de Grado July 22, 2013 5 / 42
Contents
1 What is the scope of this presentation?
2 Neutrino Oscillations in a nutshellWhat are Neutrino Oscillations?Reactor ExperimentsAccelerator experiments
CP Violation: parameter δNeutrino mass hierarchy
A key technique: off-axis neutrinos
3 Neutrino kinematicsPion rest frame - Center of MassLab Frame - Boosted Pion
Boost of the pionAngular distribution
Relation between Eν and Eπ
Pion energy distributionSummary
4 Conclusions
Neutrino Oscillations in a nutshell What are Neutrino Oscillations?
Neutrino Oscillations is aphenomenon
BEYOND THE STANDARDMODEL
predicted by Bruno Pontecorvo in1957
Basically it consists inFLAVOUR MIXING
of the different neutrino familiesOnly make sense if mν 6= 0!!
not predicted by SM
Christian Roca Catala (UV) Trabajo Fin de Grado July 22, 2013 6 / 42
Neutrino Oscillations in a nutshell What are Neutrino Oscillations?
Flavour mixing... not like this!
Christian Roca Catala (UV) Trabajo Fin de Grado July 22, 2013 7 / 42
Neutrino Oscillations in a nutshell What are Neutrino Oscillations?
... but more like this |νe〉|νµ〉|ντ 〉
=
Ue1 Ue2 Ue3
Uµ1 Uµ2 Uµ3
Uτ1 Uτ2 Uτ3
· |ν1〉|ν2〉|ν3〉
Neutrinos from a weak decay →well-defined flavour
Flavour eigenstates (e, µ, τ) 6= mass eigenstates (1,2,3) well-defined kinematics
Flavour basis and mass basis correlated by mixing matrix U (PMNS Matrix):
|να(x , t)〉 =∑
i
Uαi |νi (x , t)〉
Mass eigenstates →their evolution is given by pi ,Ei (Schrodinger img):
|νi (x , t)〉 = eipi xe−iEi t |νi 〉 = eiφi x |νi 〉 t ∼ x
NOTE!
t ∼ x since neutrinos are ultrarelativistic
Ei 6= pi for oscillations to happen, that is, mν 6= 0
Christian Roca Catala (UV) Trabajo Fin de Grado July 22, 2013 8 / 42
Neutrino Oscillations in a nutshell What are Neutrino Oscillations?
Question: thus, what are the neutrino oscillations?
Answer: an effect whereby neutrinos created with a well-defined lepton flavour (e, µ, τ)can later be measured to have a different flavour:
|ψα(x , t)〉 =∑
iβ′ U†β′ i Uαi eiφi x |νβ′〉
The oscillation is determined, thus, by the matrix Elements Uαj . This elements dependon what is called Oscillation Parameters or Oscillation Angles: θ12,θ23 and θ13
First family
Ue1 = c12c13
Uµ1 = −s12c23 − c12s23s13eiδ
Uτ1 = s12s23 − c12c23s13eiδ
Second family
Ue2 = s12c13
Uµ2 = c12c23 − s12s23s13eiδ
Uτ2 = −c12s23 − s12c23s13eiδ
Third family
Ue3 = s13e−iδ
Uµ3 = s23c13
Uτ3 = c23c13
NOTE!
The parameter δ appears in thePMNS matrix as the CP violationparameter
Christian Roca Catala (UV) Trabajo Fin de Grado July 22, 2013 9 / 42
Neutrino Oscillations in a nutshell What are Neutrino Oscillations?
Question: Which is the probability that a neutrino oscillate aftertravelling an interval L?
Answer: This depends on the medium the neutrinos travel through. The electrondensity Ne influence the cross section of charged current weak interactions of νe . Let’s
take the concrete example (νµ → νe) → it allows to measure θ13 and δ:
Oscillations through vacuum
P(νµ → νe ) = sin2 2θ13 sin2 θ23 sin2
(∆m2
13L
4E13
)+ subleading eff.
Dependence on:
|∆m2|: absolute value of squared mass difference
Oscillation parameters θ13, θ23
Subleading effects: very important for the analysis of CP violation (seen later)
The dependences give us CRUCIAL information about what can we expect fromoscillations through vacuum/matter.
NOTE!
The oscillations will always depend on the mass differences between mass familiesrelated to the oscillation ∆m2
13 = m21 −m2
3 → we will refer to it as mass difference.
Christian Roca Catala (UV) Trabajo Fin de Grado July 22, 2013 10 / 42
Neutrino Oscillations in a nutshell What are Neutrino Oscillations?
Question: Which is the probability that a neutrino oscillate aftertravelling an interval L?
Answer: This depends on the medium the neutrinos travel through. The electrondensity Ne influence the cross section of charged current weak interactions of νe .
Oscillations through matter
P(νµ → νe ) = sin2 2θ13 sin2 θ23 sin2(
∆eff13 L/2
)+ subleading eff.
Dependence on:
∆eff13 =
√(∆13 cos 2θ13 − A)2 + ∆2
13 sin2 2θ13
The sign of ∆m2: sign(∆m2)=signA
Subleading effects: very important for the analysis of CP violation (seen later)
NOTE!
The oscillations will always depend on the mass differences between mass familiesrelated to the oscillation ∆m2
13 = m21 −m2
3 → we will refer to it as mass difference.
Christian Roca Catala (UV) Trabajo Fin de Grado July 22, 2013 11 / 42
Neutrino Oscillations in a nutshell What are Neutrino Oscillations?
Summary: which implications do all this have?
Neutrino oscillation is a phenomenon beyond the SM → mν 6= 0
Flavour mixing happens due to different mass-flavour eigenstates
Oscillation probabilities depend highly on the media the neutrinos are travellingthrough
∆m2 can only be measured in experiments where neutrinos travel through matter
CPV can only be measured looking at the subleading effects (appearanceexperiments, seen later)
Christian Roca Catala (UV) Trabajo Fin de Grado July 22, 2013 12 / 42
Contents
1 What is the scope of this presentation?
2 Neutrino Oscillations in a nutshellWhat are Neutrino Oscillations?Reactor ExperimentsAccelerator experiments
CP Violation: parameter δNeutrino mass hierarchy
A key technique: off-axis neutrinos
3 Neutrino kinematicsPion rest frame - Center of MassLab Frame - Boosted Pion
Boost of the pionAngular distribution
Relation between Eν and Eπ
Pion energy distributionSummary
4 Conclusions
Neutrino Oscillations in a nutshell Reactor Experiments
Reactor Experiments
Neutrino energies ∼ MeV
Modest base-line ∼ km
Solar/atmospheric neutrinooscillation parameters via...
...Antineutrino disappearanceexperiments
Oscillations through vacuum
Christian Roca Catala (UV) Trabajo Fin de Grado July 22, 2013 13 / 42
plain Neutrino Oscillations in a nutshell Reactor Experiments
Question: What can reactor experiments measure?
Answer: Reactor experiments searching for νe disappearancemake neutrinos to oscillate into vacuum, thus the precision in
measuring θ13 is very high. A non-zero value for θ13 is aprerequisite to... →
Question: What can not reactor experiments measure
Answer: ← ... to measure the open problems in acceleratorexperiments:
Measure the mass hierarchy of neutrinos: need oscillationsin matter.
Probe CP violation in the leptonic sector leading to thepossibility that neutrino mixing violates matter/anti-mattersymmetry: need appearance experiments.
Christian Roca Catala (UV) Trabajo Fin de Grado July 22, 2013 14 / 42
plainContents
1 What is the scope of this presentation?
2 Neutrino Oscillations in a nutshellWhat are Neutrino Oscillations?Reactor ExperimentsAccelerator experiments
CP Violation: parameter δNeutrino mass hierarchy
A key technique: off-axis neutrinos
3 Neutrino kinematicsPion rest frame - Center of MassLab Frame - Boosted Pion
Boost of the pionAngular distribution
Relation between Eν and Eπ
Pion energy distributionSummary
4 Conclusions
Neutrino Oscillations in a nutshell Accelerator experiments
Accelerator Experiments
Neutrino energies ∼GeV
Long base-line ∼hundreds km
Neutrino appearanceexperiments
Oscillations throughmatter
Christian Roca Catala (UV) Trabajo Fin de Grado July 22, 2013 15 / 42
plain Neutrino Oscillations in a nutshell Accelerator experiments
CP Violation comes from subleading effects in P(νµ → νe):
Pδ(να → νβ) ∝ Jr sin δ
Remember PMNS Matrix U → the factor eδalways comes along with sin θ13.
Thus, θ13 must be measured with sensibility!! (Reactor experiments)
Question: What is CP Violation?
Answer: There are not the same physicsfor particles and antiparticles → Particle
and antiparticle symmetry is broken!!U† describes antineutrino oscillations,
eδ → e−δ:
Pδ(να → νβ) ∝ Jr (− sin δ)
Thus P(να → νβ) 6= P(να → νβ)
NOTE!
Jr = 0 IF α = β, thus disappearance experiments cannot measure CPV!!In other words, survival experiments can’t reconstruct neutrino interference generatingthose subleading effects terms.
Christian Roca Catala (UV) Trabajo Fin de Grado July 22, 2013 16 / 42
plain Neutrino Oscillations in a nutshell Accelerator experiments
Question: What is masshierarchy?
Answer: Mass hierarchy is theunknown order of the several
neutrino mass families.There are two possibles hierarchies,
depending on the sign of ∆m213:
normal hierarchy (m21 < m2
3)
inverted hierarchy (m23 < m2
1)
→ Oscillations in matter: dependon the parameter A ∝ ∆m2, thus
are sensitive to sign(∆m2)!!
NOTE!
Mass difference ∆m212 has been completely measured by solar neutrino. Since the
oscillations inside the sun are considered to occur through matter, the sign have beendetermined.
Christian Roca Catala (UV) Trabajo Fin de Grado July 22, 2013 17 / 42
plain Neutrino Oscillations in a nutshell Accelerator experiments
Christian Roca Catala (UV) Trabajo Fin de Grado July 22, 2013 18 / 42
plainContents
1 What is the scope of this presentation?
2 Neutrino Oscillations in a nutshellWhat are Neutrino Oscillations?Reactor ExperimentsAccelerator experiments
CP Violation: parameter δNeutrino mass hierarchy
A key technique: off-axis neutrinos
3 Neutrino kinematicsPion rest frame - Center of MassLab Frame - Boosted Pion
Boost of the pionAngular distribution
Relation between Eν and Eπ
Pion energy distributionSummary
4 Conclusions
plain Neutrino Oscillations in a nutshell A key technique: off-axis neutrinos
Detecting neutrinos is not impossible, butthe truth is they are very elusive!
Damn you, Pauli!
→ That’s why several techniques havebeen developed in order to attain higherenergy resolution.
“I told you!”Wolfgang Ernst Pauli
The scope of the second part of my work is to show how the off-axis neutrinos methodworks, in the same way it’s used in actual experiments like T2K and NOνA.
Christian Roca Catala (UV) Trabajo Fin de Grado July 22, 2013 19 / 42
plain Neutrino Oscillations in a nutshell A key technique: off-axis neutrinos
Question: What is off-axis neutrino technique?
Answer: We say a neutrino detector is placed off-axis when it subtends a determinednon-zero angle respect the travel line of the neutrino beam. Indeed, the neutrino beambehaves as a wave package, and it spreads out around this line. For a given neutrino’ssource energy, there is an angle off-axis where the neutrino flux have a well-defined
energy.
Christian Roca Catala (UV) Trabajo Fin de Grado July 22, 2013 20 / 42
plain Neutrino Oscillations in a nutshell A key technique: off-axis neutrinos
You may not believe me, but T2K and NOνA do! Let’s analyse theneutrino kinematics and discover the goodness of the off-axis
technique!
NOνA placed the fardetector at an off-axis angle
θ = 14mrad.
T2K placed the far detectorat an off-axis angle
θ = 44mrad.Christian Roca Catala (UV) Trabajo Fin de Grado July 22, 2013 21 / 42
plainContents
1 What is the scope of this presentation?
2 Neutrino Oscillations in a nutshellWhat are Neutrino Oscillations?Reactor ExperimentsAccelerator experiments
CP Violation: parameter δNeutrino mass hierarchy
A key technique: off-axis neutrinos
3 Neutrino kinematicsPion rest frame - Center of MassLab Frame - Boosted Pion
Boost of the pionAngular distribution
Relation between Eν and Eπ
Pion energy distributionSummary
4 Conclusions
plain Neutrino kinematics Pion rest frame - Center of Mass
Question: What are we going to study?
Answer: The process to analyse is the decay of a pion into muon and neutrino:
π− → µ− + νµ
π+ → µ+ + νµ
We’ll attack this problem from two points of view:
massless neutrino approximation → mν = 0
massive neutrino first order correction →∼ m2ν in energy and momentum
The pion at the same tame come from the collision between a beam of acceleratedprotons towards a fixed target:
p + X → π− + X + Y
NOTE!
The masses are mπ = 139.57MeV and mµ = 105.66MeV
Christian Roca Catala (UV) Trabajo Fin de Grado July 22, 2013 22 / 42
plain Neutrino kinematics Pion rest frame - Center of Mass
Massless neutrinos(arXiv:1005.0574)
In the first approximation we takemν = 0 and thus E = P
Pν = Eν = E =m2
π −m2µ
2mπ
Massive neutrinos
Taking the first order corrections∼ m2
nu, the result gives
Ecm = E +m2
i
2mπ
Pcm = E − m2i
2Eε
Christian Roca Catala (UV) Trabajo Fin de Grado July 22, 2013 23 / 42
plainContents
1 What is the scope of this presentation?
2 Neutrino Oscillations in a nutshellWhat are Neutrino Oscillations?Reactor ExperimentsAccelerator experiments
CP Violation: parameter δNeutrino mass hierarchy
A key technique: off-axis neutrinos
3 Neutrino kinematicsPion rest frame - Center of MassLab Frame - Boosted Pion
Boost of the pionAngular distribution
Relation between Eν and Eπ
Pion energy distributionSummary
4 Conclusions
plain Neutrino kinematics Lab Frame - Boosted Pion
Question: How do we do the change of coordinates?
Answer: Change from CoM Frame (pion at rest) → to Lab Frame (pion at flight)through a Lorentz boost γ for a pion travelling at β in the z-axis:
Λ =
γ 0 0 γβ0 1 0 00 0 1 0γβ 0 0 γ
Energy and momentum in Lab Frame
Applying the boost to the 4-momentum in CoM Pσlab = Λσ
δPδcm:
Elab = γ(Ecm + βPcm cos θcm)Plab sin θlab = Pcm sin θcm
Plab cos θlab = γ(Pcm cos θcm + βEcm)
We have used spherical coordinates with cylindrical symmetry → Independent ofazimutal degree of freedom ϕ
NOTE!
It does not matter to take β nor −β, that is, in direction z or −z : the results areindeed equivalent.
Christian Roca Catala (UV) Trabajo Fin de Grado July 22, 2013 24 / 42
plain Neutrino kinematics Lab Frame - Boosted Pion
Question: How can we obtain the angular distribution of the neutrino?
Answer: From the CoM angular distribution and the Jacobian of the transformation(Ecm, cos θcm → Elab, cos θlab:
1
Γ
d2Γ
dϕlabdcos θlab=
1
4πJ(cos θcm, ϕcm; cos θlab, ϕlab)
The jacobian of the transformation is easy to obtain as:
J(cos θcm, ϕcm; cos θlab, ϕlab) =
∣∣∣∣∣∣∣∣∂ cos θcm
∂ cos θlab
∂ cos θcm
∂ϕlab
∂ϕcm
∂ cos θlab
∂ϕcm
∂ϕlab
∣∣∣∣∣∣∣∣ =∂ cos θcm
∂ cos θlab
We need to calculate de derivatives of the cosines!
NOTE!
The pion decays isotropically in rest, therefore the angulardistribution in CoM:
1
Γ
dΓ
dΩcm=
1
4π
Christian Roca Catala (UV) Trabajo Fin de Grado July 22, 2013 25 / 42
plain Neutrino kinematics Lab Frame - Boosted Pion
Thus the angular distribution can be obtained from the derivatives of the cosines:
First Approximation: mi = 0,Ecm = Pcm (arXiv:1005.0574)
cos θlab =
cos θcm + β
1 + β cos θcm
cos θcm =cos θlab − β
1− β cos θlab
∂cos θcm
∂cos θlab= γ2
(1
1− β cos θlab
)2
Angular distribution:
1
Γ
dΓ
dΩlab=
1
4πγ2
(1
1− β cos θlab
)2
First order corrections ∼ m2i , Ecm 6= Pcm
cos θlab =
Pcm cos θcm + βEcm
Ecm + βPcm cos θcm
cos θcm =Ecm
Pcm
cos θlab − β1− β cos θlab
∂ cos θcm
∂ cos θlab=
Ecm
Pcmγ2
(1
1− β cos θlab
)2
Angular distribution:
1
Γ
dΓ
dΩlab=
1
4π
Ecm
Pcmγ2
(1
1− β cos θlab
)2
Christian Roca Catala (UV) Trabajo Fin de Grado July 22, 2013 26 / 42
plain Neutrino kinematics Lab Frame - Boosted Pion
Neutrino Flux in terms of θlab for several Eπ
−2 −1.5 −1 −0.5 0 0.5 1 1.5 20
2000
4000
6000
8000
10000
12000
θlab
(rad)
νµ F
lux (
Arb
itra
ry U
nits)
Summary: which implications do all this have?
Either for the approximation mν = 0 or for the first order corrections ∼ m2ν →
same results obtained!
For a fixed Eπ, neutrino flux peaks at θlab = 0
Christian Roca Catala (UV) Trabajo Fin de Grado July 22, 2013 27 / 42
plainContents
1 What is the scope of this presentation?
2 Neutrino Oscillations in a nutshellWhat are Neutrino Oscillations?Reactor ExperimentsAccelerator experiments
CP Violation: parameter δNeutrino mass hierarchy
A key technique: off-axis neutrinos
3 Neutrino kinematicsPion rest frame - Center of MassLab Frame - Boosted Pion
Boost of the pionAngular distribution
Relation between Eν and Eπ
Pion energy distributionSummary
4 Conclusions
plain Neutrino kinematics Relation between Eν and Eπ
Question: Why is important to look at the relationship between Eνand Eπ?
Answer: This relationship will lead us a hint about the energy distribution Eν of theneutrinos that we will treat in further sections.
Remember Elab obtained from the Lorentz boost → put in terms of θlab
Elab = γ(Ecm + βPcm cos θcm) =Ecm
γ
(1
1− β cos θlab
)
Maximum neutrino energy
The maximum energy is given by∂Eν
∂Eπ= 0 and this lead us the conditions:
β = cos θlab
γ = 1/ sin θlab
Thus, the maximum energy is Emax = Ecmγ
Christian Roca Catala (UV) Trabajo Fin de Grado July 22, 2013 28 / 42
plain Neutrino kinematics Relation between Eν and Eπ
Neutrino Energy in Lab Frame in terms of Pion Energy
0 5000 10000 150000
1000
2000
3000
4000
5000
6000
7000
Eπ (MeV)
Eν (
Me
V)
θ = 0 rad
θ = 0.008 rad
θ = 0.02 rad
θ = 0.06 rad
θ = 0.044 rad
θ = 0.03 rad
Summary: which implications do all this have?
For a fixed θlab, Eν has a maximum for β = cos θlab
There is a “stationarity” of Eν around Emax tending asymptotically to a constant
valueChristian Roca Catala (UV) Trabajo Fin de Grado July 22, 2013 29 / 42
plain Neutrino kinematics Relation between Eν and Eπ
Neutrino Energy in Lab Frame in terms of Pion Energy
0 5000 10000 150000
1000
2000
3000
4000
5000
6000
7000
Eπ (MeV)
Eν (
Me
V)
θ = 0 rad
θ = 0.008 rad
θ = 0.02 rad
θ = 0.06 rad
θ = 0.044 rad
θ = 0.03 rad
Summary: which implications do all this have?
Neutrinos emitted will be bunched in a energy region ∼ Emax .
Neutrino flux needs to be peaked near Emax .
Christian Roca Catala (UV) Trabajo Fin de Grado July 22, 2013 30 / 42
plainContents
1 What is the scope of this presentation?
2 Neutrino Oscillations in a nutshellWhat are Neutrino Oscillations?Reactor ExperimentsAccelerator experiments
CP Violation: parameter δNeutrino mass hierarchy
A key technique: off-axis neutrinos
3 Neutrino kinematicsPion rest frame - Center of MassLab Frame - Boosted Pion
Boost of the pionAngular distribution
Relation between Eν and Eπ
Pion energy distributionSummary
4 Conclusions
plain Neutrino kinematics Pion energy distribution
Question: What does it happen if pion has not a definite energy buta given energy spectrum?
Answer: What we get from the collision proton → fixed target is a non-linear energyspectrum for pions (arXiv:1005.3692). This spectrum have to be implemented in the
analysis of the neutrino distribution: (Eπ, cos θcm)→ (Elab, cos θlab):
1
Γ
d2Γ
dEdΩlab=∝ (Ep − Eπ)5 · J(Eπ, cos θcm; Elab, cos θlab)
This time the jacobian is:
J(Eπ, cos θcm; Elab, cos θlab) =
∣∣∣∣∣∣∣∣∂Eπ
∂Elab
∂ cos θcm
∂Elab
∂Eπ
∂cosθlab
∂cosθcm
∂ cos θlab
∣∣∣∣∣∣∣∣NOTE!
The energy spectrum for the pions F(Eπ,Ep) we have taken comes from the results ofNA61/SHINE Collaboration (arXiv:1005.3692):
1
Γ
d2Γ
dEπdΩcm∝ (Ep − Eπ)5
Christian Roca Catala (UV) Trabajo Fin de Grado July 22, 2013 31 / 42
plain Neutrino kinematics Pion energy distribution
Neutrino Flux in terms of Eπ for Off-axis Angles θlab > 0.01
2000 2500 3000 3500 4000 4500 50000
0.5
1
1.5
2
2.5x 10
4
Eπ (MeV)
νµ F
lux (
Arb
itra
ry U
nits)
θ = 0.06 rad θ = 0.05 rad
θ = 0.044 rad
θ = 0.04 rad
θ = 0.03 rad
1
Γ
d2Γ
dEdΩlab∝ (Ep − Eπ)5 mπβ
Pcm(cos θlab − β)
Christian Roca Catala (UV) Trabajo Fin de Grado July 22, 2013 32 / 42
plain Neutrino kinematics Pion energy distribution
Neutrino Flux in terms of Eπ for Off-axis Angles θlab > 0.01
2000 2500 3000 3500 4000 4500 50000
0.5
1
1.5
2
2.5x 10
4
Eπ (MeV)
νµ F
lux (
Arb
itra
ry U
nits)
θ = 0.06 rad θ = 0.05 rad
θ = 0.044 rad
θ = 0.04 rad
θ = 0.03 rad
Summary: which implications do all this have?
For any Off-axis angle only a small region of Eπ contributes.
Singularity at cos θlab = β appears: maximum energy Emax condition!Christian Roca Catala (UV) Trabajo Fin de Grado July 22, 2013 33 / 42
plain Neutrino kinematics Pion energy distribution
Neutrino Flux in terms of Elab for θlab = 0.044
660 665 670 675 680 685 690 695 7000
100
200
300
400
500
600
700
800
900
1000
Eν (MeV)
νµ f
lux (
arb
itra
ry u
nits)
Summary: which implications do all this have?
Off-axis angles peaks the neutrino flux in a narrow neutrino energy region.
Neutrinos with higher energy than Emax are essentially absent.
Christian Roca Catala (UV) Trabajo Fin de Grado July 22, 2013 34 / 42
plain Neutrino kinematics Pion energy distribution
Neutrino Flux in terms of Elab for near on-axis angles θlab < 0.01
0 2000 4000 6000 8000 10000 12000 140000
5
10
15
20
25
30
35
40
Eν (MeV)
νµ flu
x (
arb
itra
ry u
nits)
θ = 0
θ = 0.001
θ = 0.002
θ = 0.003
θ = 0.004
Summary: which implications do all this have?
On-axis angles give higher integrated flux but less energy resolution.
On-axis angles also peaks the flux but for energies higher than parent pion energy→ cos θlab ∼ 1.
Christian Roca Catala (UV) Trabajo Fin de Grado July 22, 2013 35 / 42
plainContents
1 What is the scope of this presentation?
2 Neutrino Oscillations in a nutshellWhat are Neutrino Oscillations?Reactor ExperimentsAccelerator experiments
CP Violation: parameter δNeutrino mass hierarchy
A key technique: off-axis neutrinos
3 Neutrino kinematicsPion rest frame - Center of MassLab Frame - Boosted Pion
Boost of the pionAngular distribution
Relation between Eν and Eπ
Pion energy distributionSummary
4 Conclusions
plain Neutrino kinematics Summary
Summary
Massless neutrinos mν = 0 and first order correction ∼ m2ν approximations are
equivalent
Neutrinos attain a maximum energy Emax , independent of the pion energy, forβ = cos θlab.
Neutrinos bunch in a small energy region Eν ≤ Emax
For every energetic region for the parent pion there is an off-axis angle whichpeak the neutrino flux for β = cos θlab
The relative narrowness of the off-axis beam increase the energy resolution ofthe neutrino beam.
Christian Roca Catala (UV) Trabajo Fin de Grado July 22, 2013 36 / 42
plainContents
1 What is the scope of this presentation?
2 Neutrino Oscillations in a nutshellWhat are Neutrino Oscillations?Reactor ExperimentsAccelerator experiments
CP Violation: parameter δNeutrino mass hierarchy
A key technique: off-axis neutrinos
3 Neutrino kinematicsPion rest frame - Center of MassLab Frame - Boosted Pion
Boost of the pionAngular distribution
Relation between Eν and Eπ
Pion energy distributionSummary
4 Conclusions
plain Conclusions
New results from SuperK far detector of T2K - 19th July,2013 (3 days ago!)
νe appearance confirmation at the 7.5σ level of significance.“Observation of this new type of neutrino oscillation leads the way to new studies ofcharge-parity (CP) violation which provides a distinction between physical processes
involving matter and antimatter.”T2K announcement
Christian Roca Catala (UV) Trabajo Fin de Grado July 22, 2013 38 / 42
plain Conclusions
We DO know neutrinos exist.
We DO know about their flavour oscillations.
We DO know matter and antimatter annihilate.
Christian Roca Catala (UV) Trabajo Fin de Grado July 22, 2013 39 / 42
plain Conclusions
Next generation accelerator experiments would discovereventually the divergence between neutrino-antineutrino oscillations
→ CP symmetry breaking.
This asymmetry would generate the so-called Leptogenesis,happening responsible of the residual existing after
matter-antimatter annihilation just after the Big Bang... butcalling it residual seems a bit pejorative, isn’t it?
Christian Roca Catala (UV) Trabajo Fin de Grado July 22, 2013 40 / 42
plain Conclusions
Why not to call it...Universe?
Christian Roca Catala (UV) Trabajo Fin de Grado July 22, 2013 41 / 42
plain Conclusions
THANKS FOR WATCHING!
“This is not even wrong!” Wolfgang Ernst Pauli, again...
Christian Roca Catala (UV) Trabajo Fin de Grado July 22, 2013 42 / 42
plain Conclusions
Kirk T. McDonald (6 November 2001) “An Off-Axis Neutrino Beam” Princetonhttp://www.hep.princeton.edu/~mcdonald/examples/offaxisbeam.pdf
Jean-Michel Levy (6 May 2010). “Kinematics of an off axis neutrino beam”http://arxiv.org/abs/1005.0574
Carlo Giunti (4 January 2008) “Neutrino Flavor States and the Quantum Theory ofNeutrino Oscillations” http://arxiv.org/pdf/0801.0653v1.pdf
Hiroshi Nunokawa, Stephen Parke, Jose W. F. Valle (2 October 2007) “CPViolation and Neutrino Oscillations” http://arxiv.org/pdf/0710.0554v2.pdf
Gina Rameika (20 May 2006) “Off-Axis Neutrinos” Fermilabhttp://www.phy.bnl.gov/~diwan/talks/talks/nusag-may-20/NuSAG_052006_
_offaxis.pdf
The T2K Collaboration (8 June 2011). “The T2K Experiment”http://arxiv.org/abs/1106.1238
The T2K Collaboration (3 April 2013). “Evidence of Electron Neutrino Appearancein a Muon Neutrino Beam”http://arxiv.org/abs/1304.0841
The T2K Collaboration (6 November 2005) “ND280 Conceptual Design Report(Internal Report)” www.nd280.org/documents/cdr.pdf/download
Christian Roca Catala (UV) Trabajo Fin de Grado July 22, 2013 42 / 42
plain Conclusions
John N. Bahcall and Raymond Davis Jr. (1976) “Solar Neutrinos: A ScientificPuzzle”, Science, 191, 264
NOνA Collaboration (21 March 2005) “The NOνA Experiment”http:
//nova-docdb.fnal.gov/0005/000593/001/NOvA_P929_March21_2005.pdf
CHOOZ Collaboration (15 November 1999) “Initial Results from the CHOOZ LongBaseline Reactor Neutrino Oscillation Experiment”http://arxiv.org/pdf/hep-ex/9711002v1.pdf
SuperKamiokande Collaboration (14 May 2001) “Super-Kamiokande atmosphericneutrino results” http://arxiv.org/pdf/hep-ex/0105023v1.pdf
SNO Collaboration (2 August 2004) “Results from the Sudbury NeutrinoObservatory”http://www.slac.stanford.edu/econf/C040802/papers/WET001.PDF
CHOOZ Collaboration (13 June 2003) “Search for neutrino oscillations on a longbase-line at the CHOOZ nuclear power station”http://arxiv.org/pdf/hep-ex/0301017v1.pdf
Daya Bay Collaboration (2012) “Observation of electron-antineutrinodisappearance at Daya Bay” http://arxiv.org/pdf/1203.1669.pdf
Christian Roca Catala (UV) Trabajo Fin de Grado July 22, 2013 42 / 42
plain Conclusions
RENO Collaboration (8 April 2012) “Observation of Reactor Electron AntineutrinoDisappearance in the RENO Experiment”http://arxiv.org/pdf/1204.0626v2.pdf
Andre de Gouvea, James Jenkins and Boris Kayser (23 March 2005) “NeutrinoMass Hierarchy, Vacuum Oscillations, and Vanishing |Ue3|” Fermilabhttp://arxiv.org/pdf/hep-ph/0503079v2.pdf
Hisakazu Minakata, Hiroshi Nunokawa, Stephen Parke (23 January 2013) “TheComplementarity of Eastern and Western Hemisphere Long-Baseline NeutrinoOscillation Experiments” http://arxiv.org/abs/hep-ph/0301210
K. Nakamura (2010). “Review of Particle Physics”
Double Chooz Collaboration (30 October 2006) “Double Chooz: A Search for theNeutrino Mixing Angle θ13” http://arxiv.org/pdf/hep-ex/0606025v4.pdf
Rabindra N. Mohapatra and Palash B. Pal (November 1990) “Massive neutrinos inphysics and astrophysics” World Scientific
NA61 Collaboration (2012) “Hadron production measurement from NA61/SHINE”University of Genevahttp://indico.cern.ch/getFile.py/access?contribId=0&resId=
0&materialId=3&confId=183449Christian Roca Catala (UV) Trabajo Fin de Grado July 22, 2013 42 / 42