[Isac-journal-club] Reminder: Journal club today

Jack Henderson jhenderson at triumf.ca
Wed Sep 28 15:19:32 PDT 2016


There's a problem with today's room booking. We're currently looking for an
alternative room...

On Wed, Sep 28, 2016 at 12:52 PM, Jack Henderson <jhenderson at triumf.ca>
wrote:

> SNACKS
>
> *This weeks paper:*
> A week from now, we will congregate to go over the paper: “Search for
> Majorana neutrinos near the inverted mass hierarchy region with KamLAND-Zen”
>
> http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.117.082503
>
> The questions and helpful information provided by this week's
> speaker Charlie Payne.
>
> *Questions*
>
>
> 1) How can a detector measure a process with a half-life supposedly many
> orders of magnitude longer than the age of the universe?
>
>
> 2) And why should we care about the neutrinoless double-beta decay (0vBB)
> half-life anyways?
>
>
> 3) True or False - a positive measurement of 0vBB would necessarily
> confirm that: a) the neutrino is its own anti-particle, b) the neutrino is
> Majorana, c) lepton number is violated via physics beyond the standard
> model?
>
>
> 4) What’s the significance of KamLAND-Zen probing into the edge of the
> “quasidegenerate” mass region?
>
>
> 5) How do they distinguish potential 0vBB events from other events, such
> as: 2vBB, contamination/background, other exotic processes, etc?
>
> *Specific discussion questions*
>
>
> 6) The authors speculate that “much of [the Ag-110m contaminant] settled
> to the bottom of the IB” (end of page 3), how could they test this
> hypothesis? Is splitting the phase 2 data into two periods, as defined by
> the Ag-110m lifetime, helpful to this analysis in that respect?
>
>
> 7) Overall, with these results and the planned upgrades (mentioned in the
> conclusions), is it fair to conclude that KamLAND-Zen will be a competitive
> detector with a demonstrated ability to measure the hypothetical 0vBB?
>
>
> 8) And if so, how does the conclusion of zero events measured (and hence
> only having *constraints* on the 0vBB half-life) fair for the outlook of
> future 0vBB work, in particular with respect to the quasidegenerate mass
> region and beyond.
>
>
>
> *Jargon to help with your reading*
>
>
> * Ag-110m = a nuclear isomer (a metastable nuclear state in excitation -
> hence the “m”) of silver
>
>
> * quasidegenerate neutrino mass region = from neutrino oscillation
> experiments we can tell there must be a non-zero relative mass scale of the
> three neutrino mass eigenstates, and these fit into two hierarchies (the
> normal (NH) and inverted (IH)) which overlap at certain points referred to
> as quasidegenerate, where said 0vBB data would find NH and IH
> indistinguishable, see FIG 3 for a nice diagram of the current situation
>
>
> * nuclear matrix elements = theoretical calculations of the underlying
> nuclear physics of a process, for example using ab-initio many-body theory;
> which can predict half-lifes, given the masses of the constituents of said
> process are known, or visa versa (wink wink, nudge nudge, say no more)
>
>
> * spallation = the process of being broken apart into pieces upon impact,
> for example nuclear matter being spalled by high energy muons bouncing
> around
>
> --
> Dr Jack Henderson
> TRIUMF
> 4004 Wesbrook Mall
> Vancouver BC, V6T 2A3
> Canada
>
> Phone: +1-604-222-1047 Ex. 6301
> Fax: +1-604-222-1074
>



-- 
Dr Jack Henderson
TRIUMF
4004 Wesbrook Mall
Vancouver BC, V6T 2A3
Canada

Phone: +1-604-222-1047 Ex. 6301
Fax: +1-604-222-1074
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