Long base-line experiments at  Searches for Neutrino Oscillations  The CERN experimental programme

The COSMOS experiment at Fermilab

This experiment uses the neutrino beam which will become available at Fermilab near the end of the century when the new Main Injector (MI) will start operation. The COSMOS experiment is conceptually similar to CHORUS. Table  compares the main parameters of the future Fermilab Main Injector and neutrino beam with those presently available from the CERN SPS. It must be pointed out that the cross-section for $\tau^{-}$ production from $\nu_{\tau}'s$ in the neutrino beam from the Fermilab Main Injector is a factor of $\sim 5$ lower than in the CERN beam because of the lower energy of the interacting neutrinos.  

Table: List of relevant parameters for the present CERN neutrino beam and for the anticipated beam from the Fermilab Main Injector (MI)

   

	CERN SPS	Fermilab MI
Protons energy	450 GeV	120 GeV
Protons on target/cycle	$2 \times 10^{13}$	$6 \times 10^{13}$
Cycle time	14.4s	1.9s
Protons on target/year	$1.2 \times 10^{19}$	$3 \times 10^{20}$
Average energy of interacting $\nu_\mu$	40 GeV	16 GeV

 

 

COSMOS will start data taking around the year 2000. Figure 2 shows the region of the $\sin^{2}2\theta,\Delta$m² plane which will be excluded by COSMOS if no oscillation signal is observed, together with the anticipated combined CHORUS and NOMAD limit.

  

Figure: Region of the $\sin^{2}2\theta,\Delta$m² plane excluded by COSMOS after a four-year run if no $\nu_\mu$ signal is observed. Also shown is the anticipated limit from CHORUS and NOMAD, together with limits from previous experiments.