Design Optimisation Studies for a new beta-decay
neutrino mass experiment
Why the project?
Sparsh Navin, Dr. Y. A. Ramachers
AMBER (Anti-Neutrino Mass Balance using
Electrostatics and Radioactivity)
•Direct neutrino mass measurement
The most interesting region of
the beta spectrum to neutrino
physics is the final 10eV of the
energetic electrons emitted
from the source. (Accompanying
picture shows a
tritium source, similar for nickel source)
•Beta-decay end point experiment
With the present set up it takes more than 2000 years to get close to the
end point.
•Uses Ni-63 as electron current source to charge
capacitor
Aim – decrease running time of the
•Capacitor is a levitating ball suspended by magnets
Electrons that hit the
target sphere are
detected.
experiment
•Increase flux (area of source)
COMSOL Multiphysics-Electromagnetics module
•Based on partial differential equations
•Solves using finite element method
Model geometry
Generate mesh
Apply boundary
conditions
Solve and post
process
Learning Outcomes:
•Target and priority setting to meet deadlines
•Reporting and presenting work and findings
•Literature search and scientific writing
•Working as a member of a research group
•Data handling and logging
•Decrease capacitance C=ΔQ/ΔV
Doubling area of source doubles
flux but only increases capacitance
slightly (0.6% increase). Major
contributor to capacitance of ball
is the box around it.
R
E
S
1 source:
U
C=6.964x10-13F
L
Two sources
(flux x 2)
T
C=6.301 x 10-13F
S
Challenges: Greater accuracy in
geometry implies more elements in the
mesh generated => lesser accuracy of the
calculated result (and it takes longer).
A fairly accurate geometry without too
much detail gives a good approximation.
Particle traces
show that only
electrons with
high velocity hit the ball.
Bringing the source closer to the
ball increases capacitance only
linearly but flux increases as
shown.
In the present
set up the source
is 5 cm from the
ball.
Possible extension: spherical
source surrounding the sphere
=>maximum surface area,
moderate capacitance values