next up previous contents
Next: Neutrino-electron scattering Up: Neutrino Experiments at Reactors Previous: Status of deuteron experiments

Neutrino Oscillation Search

The only channel which can be studied in a reactor experiment is the disappearance of $\bar\nu_e$. The signature of the $\bar\nu_e$ interaction is the inverse $\beta$ decay. CC reaction is forbidden for other neutrinos ( $\nu_{\mu},\nu_{\tau}$) at the energies of reactor neutrinos. As a consequence the sensitivity in mixing is limited to few $\%$ but the $\delta m^{2}$ sensitivity can be extended up to 10-3 eV2. During the last 15 years many experiments have been conducted to search for neutrino oscillation at distances ranging from 8m to 70m. No disappearance effect have been observed. From these experiments the limits on oscillation parameters are listed in table [*].
Table:limits on oscillation parameters 
 
$\delta m^{2}$
 
$sin^{2}(2\theta)$
$7*10^{-2}< \delta m^{2} < 2 eV^{2}$ 
$\delta m^{2} > 2 eV^{2}$ 
$ \delta m^{2} < 10^{-2} eV^{2}$
< 10-1 

< 4*10-2 

full mixing
 

 
 

To extend the sensitivity in $\delta m^{2}$ to 10-3 eV2 detectors have to be located at a distance as large as 1km. The domain covered will allow to probe the $\nu_{e} - \nu_{\mu}$ transition to solve the atmospheric neutrino anomaly. The challenge is to compensate the neutrino flux reduction (10-4) by reducing the cosmic ray induced background in the detector. Two experiments have proposed two different concepts to reduce the background:

The next logical step will be to implement an experiment at a distance larger than 10km in order to search for $\nu$ oscillation down to 10-4eV2. The interest of such a search should be studied on the basis of the results of the ongoing experiments (reactor, atmospheric $\nu$, solar $\nu$). To get a neutrino event rate of 10 events per day the target size is of the order of 1 Kton. The IMB site, 13 km away from the 3600 Mwth Perry reactor, is a good candidate with an overburden of 1570-mwe. Another site is studied in Japan 60 km away from a reactor. Research and development are needed on scintillators (light transmission, stability, radio-purity) before to be able to run a 1Kton detector. Other field of physics will be accessible with such a detector: proton decay, supernova, solar neutrino. The experience from the large underground detector in preparation like Borexino will be useful in that study. 
next up previous contents
Next: Neutrino-electron scattering Up: Neutrino Experiments at Reactors Previous: Status of deuteron experiments 

NuPECC WebForce,