1. Monoenergetic Neutrino Beam for Long Baseline Experiments
Joe Sato (Saitama & TUM)
hep-ph/ Joe Sato
hep-ph/05????? Mark Rolinec , Joe Sato

2. Introduction Precision Measurement
　Precise Energy Determination for Neutrino
New Idea to determine Neutrino Energy at a Detector ?

3. Basic Idea Control Neutrino Energy and Get Monoenergetic Neutrino Beam
Electron Capture
Neutrino Energy at Rest ：Definite
Boosting Mother Nuclei by
Control Neutrino Energy and Get Monoenergetic Neutrino Beam

4. Experimental Setup
Concept
Ionized
Neutral
Injection
Remove

5. Condition on (and ) Neutrino Energy in Lab (Which Energy Range ?)
Highest Energy
(Which Energy Range ?)
Assuming a beam pointing to a detector:
At first glance
determines

6. to get higher intensity beam
Neutrinos “fly”
Baseline in rest frame
Inverse of “Quality Factor” (Zucchelli)
Larger
Preferable
to get higher intensity beam
Lower
better

7. Find a nuclei with lower
Longer lifetime
However, Lower
for mother nucleus
Constraint from “our (experiment)” lifetime
: At most several years
Upper bound for
“Lower bound” for
Find a nuclei with lower
and shorter

8. Theoretical Aspects Neutrino Energy in rest frame
Case (i) : Purely monoenergetic neutrino
No positron emission
Consider
4.11 hour
Mass difference Excited Energy Binding Energy
Neutrino Energy in rest frame

9. Acceleration of
Baseline in the rest frame
　L independent
　　(Q dependent)

10. For “All/2” hit a detector with diameter D=176m! Lifetime in lab
Oscillation maximum is covered
Lifetime in lab
Baseline length in the rest frame
“All/2”
hit a detector with diameter D=176m!
Detector
Rest frame of
2D (= )m
176m

11. Compare Very Preliminary
0.01% (nufact) ,1% (beta beam) neutrinos are used
Comparable with
Very Preliminary
NO optimization, rough estimate

12. Neutrino Energy as a function of R
Detector position from beam center
For a detector size D
For example
Very wide range of neutrino energy

13. Energy resolution Much better than others
For the position resolution
～ 30 cm for SK
Energy uncertainty is related with δR
Much better than others
Detection Position = Neutrino Energy !!

14. Energy Distribution neutrino beam uniformly distributed in its energy
In a solid angle
in rest frame
the number of neutrinos distribute uniformly
The solid angle is related with detector position
neutrino beam uniformly distributed in its energy
Optimum , baseline ? How large detector ?
Under consideration

15. Candidate Nucleus
Up to A=114

16. Case (ii) : Monoenergetic and Continuous energy neutrinoIf
Both Electron capture and Positron Emission occur
Still Lower Q Nucleus
Energy distribution in rest frame

17. Optimum combination of ‘s ?
is high
is small
At a detector, neutrinos from EC are monoenergetic
EC dominates in decay of
By varying
we can survey oscillation with definite energy resolution
Optimum combination of ‘s ?

18. both line spectrum and continuum spectrum ?
EC and
Emission almost half and half
Can we make use of
both line spectrum and continuum spectrum ?
Appropriate ?
First maximum ?
Second maximum ?

19. Summary and Discussion
Electron Capture :
Definite Neutrino Energy at rest frame
Control Neutrino Energy at lab by boosting mother nuclei
For very low
Very large
If large enough, almost all neutrinos hit a detector
Very efficient use of neutrinos
Very good “quality factor”

20. Neutrino energy as a function of detector position
Furthermore we can survey very wide range of neutrino energy simultaneously and energy is extremely “measured” by the detector position
Neutrino energy as a function of detector position
Simultaneous experiment with definite energy
Position is determined very precisely
Can we remove backgrounds more efficiently !?

21. For not low Both Electron capture and Positron Emission occur
EC dominates in decay of
Monoenergetic Neutrino at a detector due to lower
By varying
we can survey oscillation with definite energy resolution
EC and
Emission almost half and half
Efficient ?
Making use of both continuous and line spectrum?

22. 1. Even under a usual beta beam context,
Discussion
1. Even under a usual beta beam context,
Is better candidate than ?
Merit 1: lower Q
633 KeV ( positron emission)
3935 KeV
Lower Q value by 6
Less nuclei by 40
Merit 2: much easier to create
Even a medical doctor can create
Demerit : longer life ... But,
If we can circulate nuclei during one month or more,
will be better source

23. 2. Other Problems CP/T conjugate channels?
How to create anti-neutrino beam ?
How to create muon-neutrino beam ?
Otherwise
Rely on parameter fitting?
Some of Correlation resolved
Very Preliminary
No optimization

24. ありがとうございました
(Arigatou Gozaimashita)
Vielen Danke