R&D for a neutrino mass
determination experiment using
the AMBER technique
Y. A. Ramachers
University of Warwick
Y.A. Ramachers
PPRP Meeting Durham 09/03/06
Outline
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Our group
The basic idea of AMBER
Current status of the prototype
Summary of proposal
Y.A. Ramachers
PPRP Meeting Durham 09/03/06
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The AMBER group
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Dr Y. A. Ramachers, Lecturer EPP
Dr M. Hadley, Theory
Mr A. Lovejoy, Head of electronics workshop
Mr J. Thornby, postgraduate student
Ms D.Y. Stewart, postgraduate student
Ms S. Navin, undergrad. student, starting June 06
Support from surface physics group, Dr G. Bell, for
vacuum chamber & R. Johnston, gold/nickel plating
Y.A. Ramachers
PPRP Meeting Durham 09/03/06
The basic idea
Radioactive beta-decay source
Principle: measure voltage in time from charging of capacitor to high precision
Observable: integrated beta-spectrum → reconstruct beta-spectrum shape.
Y.A. Ramachers
PPRP Meeting Durham 09/03/06
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Precision voltage measurements for
beta-decay: benefits
Energy-resolution effect
on end-point measurement
ΔE = 0.01 eV
Y.A. Ramachers
mν = 0.2 eV
Beta-Decay of
Ni-63,
Q=66.945 keV
ΔE = 0.93 eV
PPRP Meeting Durham 09/03/06
Solutions to basic challenges
• Non-invasive voltage measurement: inverse
Kelvin-probe
• Insulation of receiving capacitor plate:
Magnetic levitation in vacuum
• High voltage (~70 kV) stability: custommade controller in-house (developed
already for the COBRA experiment)
Y.A. Ramachers
PPRP Meeting Durham 09/03/06
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Current Status of Prototype
Prototype works!
Y.A. Ramachers
PPRP Meeting Durham 09/03/06
Current Status of Prototype
• Rough performance guide:
– Voltage measurement, 10mV precision
achieved, 1mV precision possible
– Levitation circuit μW power, extremely stable
– HV-power supply, stability to at least 10mV –
achievement by sacrificing absolute voltage
measurement for rate-of-change stability, needs
separate calibration (Cd-109 source, AMBER
technique)
Y.A. Ramachers
PPRP Meeting Durham 09/03/06
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Proposal Summary
• New measurement concept proposed: replace
energy with voltage observable.
• Non-invasive, high precision voltage measurement
achieved, independent of absolute voltage (zero
measurement technique).
• Insulate receiver by magnetic levitation in vacuum
(achieved).
• Use radioactive source as current source (to be
demonstrated).
• Propose potential high-sensitivity direct neutrino
mass measurement. All components together to be
demonstrated within two years.
Y.A. Ramachers
PPRP Meeting Durham 09/03/06
Funding Request
• Funding for man-power; RA, technician
• Modest funding for equipment – upgrade
current prototype
• Travel to conferences for dissemination
Y.A. Ramachers
PPRP Meeting Durham 09/03/06
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Long-term objective
• Increase source luminosity
• Measure Beta-spectrum shape from Q-10eV
to Q-value including atomic energy loss
effect steps → first chance to see neutrino
mass.
• Measure neutrino mass with sensitivity few
times voltage resolution, i.e. few ten meV.
Y.A. Ramachers
PPRP Meeting Durham 09/03/06
Current Status of Prototype
Levitation Circuit
Pick-up circuit of
inverse Kelvin probe
Y.A. Ramachers
PPRP Meeting Durham 09/03/06
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Anticipated Risks
• Vibrations: Voltage measurement sensitive to
capacitance – vibration-isolate vacuum chamber,
keep structure inside mechanically rigid.
• Background beta-decays: Eventually surround setup with Lead – very pure intrinsically, Pb-210
beta-decay lower Q-value than Ni-63.
• Other background charged radiation will lead to
random reset of charge collection rather than
systematic error on integrated charges.
Y.A. Ramachers
PPRP Meeting Durham 09/03/06
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