[BDXlist] [EXTERNAL] JPOS white paper - dark sector searches at JLab with a positron beam

[Andrea Bianconi]

Hi. After a more careful reading. There are a few points I do not
understand about the method of the thick target.

When the positron enters the target, I expect to see some rare
annihilations into hadrons, a few hard photons (that could be detected) but
most of the energy lost in soft forms (photons and far scattering). And the
bulk of the annihilations taking place when the positron is almost at rest
or at rest (1/s factor in cross section).
In a regular annihilation you may see the annihilation products and
reconstruct all that is needed. In the searched event case, simply nothing
should be seen, so also this concept of "missing energy" is not clear to
me. In the introduction is defined as the difference between beam and
detected energy, but this is a little generic.

I think that some more details on this part could help. I don't know, for
example describing a standard event (diagram apart).

The other technique (thin target) is more straightforward to understand.

Bye
andrea
















On Tue, May 19, 2020 at 10:06 AM Andrea Celentano <
andrea.celentano at ge.infn.it> wrote:

> Dear BDX colleagues,
> Jefferson Laboratory recently started to investigate the physics potential
> of experiments making use of a future, possible positron beam at this
> facility, ranging from traditional hadron physics measurements to
> beyond-standard-model searches.
> These ideas have been recently discussed at the JPOS17 meeting (
> https://www.jlab.org/conferences/JPos2017/), organized with the support
> of the INFN community. The idea of exploiting this beam for dark photon and
> light dark matter searches was presented at this conference: Paolo Valente
> first gave an introductory talk concerning dark sector searches with
> positrons (jpos17_valente_compressed.pptx
> <https://www.jlab.org/indico/event/206/session/25/contribution/87/material/slides/0.pptx>),
> followed by a talk from Luca Marsicano (Luca_Marsicano_JPOS17.pdf
> <https://www.jlab.org/indico/event/206/session/25/contribution/91/material/paper/0.pdf>)
> discussing the possibility of a positron beam, thin-target “PADME-like”
> experiment.
>
> At the moment, the possibility of running a positron beam at JLab is at
> the proposal level, but the community is working coherently to make this
> real in the near future. As a follow-up, a White Paper collecting ideas for
> experiments at Jefferson Lab with a future positron beam is currently being
> prepared. We drafted a document describing both a thin-target and a
> thick-target experiment: you find it attached. The list of authors is
> clearly not final, we are working on it.
>
> In particular, we think that the thin-target experiment can be run
> starting from the day-1 of the JLab future positron era, benefitting from
> the equipment and the experience of the existing PADME experiment. The
> thick-target experiment, instead, will require some dedicated R&D, both on
> the detector and on the accelerator, and thus we foresee it as a future
> step.
>
> We invite you to send us comments for this document, and we also ask you
> if you are interested to sign it. To do so, please send your contribution
> to Andrea Celentano (andrea.celentano (at) ge.infn.it).
> We’d like to ask you to within one week, before Sunday, May 24th.
>
> Thanks,
>
> Bests,
> Andrea, Luca, Marco, Mauro, Paolo
>
> _______________________________________________
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>

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