Speaker
Mr.
Pablo Fernández
(UAM)
Description
The GADZOOKS! project pursues the upgrade of the Super-Kamiokande (SK)
detector as a way to efficiently detect thermal neutrons. Inverse beta
decay reactions, as well as charged current quasi-elastic (CCQE)
scattering of low energy anti-neutrinos (up to a few hundreds of MeV) in
SK, produce one positron and one neutron in the final state. Being able
to observe the final state neutron in coincidence with the prompt positron
would mean that SK could identify these reactions as genuine with very
high confidence.
GADZOOKS! will open to Super-Kamiokande - and water Cherenkov detectors in
general - a wealth of physics currently inaccessible due to background
limitations. The most important is observing for the first time the
diffuse supernova neutrino background: Super-Kamiokande enriched with
gadolinium will discover it after few years of running.
In GADZOOKS! we will dissolve a Gadolinium (Gd) salt in the water of SK at
a loading of 0.2% by mass. The Gd has an enormous absorption cross section
for thermal neutrons, emitting in the process an ~8 MeV gamma cascade
measurable by SK. Thus, by a double coincidence in space and time of the
signals recorded by SK from the positron and the ~8 MeV gamma cascade from
the Gd-capture of the neutron, low energy anti-neutrinos interacting in
the detector will be identified with a large efficiency, > 80%.
The main R&D program towards GADZOOKS! is EGADS: a 200 ton fully
instrumented tank built in a new cavern in the Kamioka mine. EGADS
incorporates all the necessary subsystems to make GADZOOKS! a reality,
namely pretreatment, selective filtration, monitoring of different
parameters (water transparency, Gd concentration...) and Gd recovery. In
this contribution we will describe EGADS, we will present its current
status and discuss the main results and conclusions arrived at so far. In
addition, we will analyze other issues specific to the running of
GADZOOKS!, like radiopurity, CCQE reconstruction, and its impact to other
SK measurements.
Primary author
Mr.
Pablo Fernández
(UAM)