.. Filename:          projects.rst
.. Description:       homepage projects file
.. Author:            Clément Buton <cbuton@ipnl.in2p3.fr>
.. Author:            $Author: cbuton $
.. Created on:        $Date: 2014/03/12 23:33:43 $
.. Modified on:       2015/02/06 13:58:43
.. Copyright:         2014, Clément BUTON
.. $Id: projects.rst, 2014/03/12 23:33:43 cbuton Exp $

=============
 _`Projects`
=============

From  10/01/2006 to  31/12/2013, I  was  deeply involved  in the  Nearby
SuperNova             Factory            project             (`SNfactory
<http://snfactory.lbl.gov>`_). During  this period I studied  for my PhD
both at IPNL in Lyon (France) and  LBNL in Berkeley (USA), then I worked
as a Postdoc at the Unversity  of Bonn (Germany).  As from 01/01/2014, I
became  a  permanent author  of  the  collaboration.  In  the  SNfactory
project,  I   was  especially  involved   in  the  development   of  the
spectro-photometric  flux calibration  and analysis  of the  3D integral
field spectrograph `SNIFS <http://snfactory.in2p3.fr>`_.

From  01/01/2013  to  31/08/2014,  I  was a  member  of  the  `CHiPSpeCT
<http://imxgam.in2p3.fr/CHiPSpeCT.php>`_  consortium  dedicated  to  the
development  and characterization  of  the  hybrid-pixels quantum  X-ray
detectors  (XPAD).   I  was  in   charge  of  the  development  of  the
acquisition and calibration pipeline for the collaboration.

As    from    01/09/2014,    I     am    working    in    the    `emCMOS
<http://www.ipnl.in2p3.fr/spip.php?rubrique75>`_    group    at    `IPNL
<http://www.ipnl.in2p3.fr>`_  on the  MultiMOS project  in collaboration
with  the  international  company `E2V  <http://www.e2vtech.fr>`_  which
develop  the chips.   My  work constists  essentially  on analysing  and
characterizing Electron Multiplying CMOS (emCMOS) chips.

-------------------------------------------------------------------------------

_`MultiMOS`
===========

_`Electron Multiplying CMOS`
----------------------------

Scientific  low light  imaging devices  benefit today  from designs  for
pushing  the  mean noise  to  the  single  electron level.   When  noise
reduction reaches  its limit,  Signal-to-Noise Ratio improvement  can be
driven  by   an  electron  multiplication  process,   driven  by  impact
ionization,  before adding  the  readout noises.   This concept  already
implemented  in CCD  structures  using extra-pixel  shift registers  can
today be integrated  inside each pixel in CMOS  technology.  The `emCMOS
<http://www.ipnl.in2p3.fr/spip.php?rubrique75>`_    group    at    `IPNL
<http://www.ipnl.in2p3.fr>`_ is in charge of the characterization of new
prototypes  developed  by   `E2V  <http://www.e2vtech.fr>`_  using  this
concept : the  electron multiplying CMOS (emCMOS).   The CMOS technology
enables electron multiplication inside  the photodiode itself, and thus,
an overlap of  the multiplication and the integration  of the electrons.

.. image:: _static/images/pixel_structure.pdf
   :width: 400 px
   :align: center

-------------------------------------------------------------------------------

_`CHiPSpeCT & XPAD`
===================

_`Hybrid pixel detectors`
-------------------------

Modern X-ray  imaging systems allow  to obtain images  immediately after
exposure. The  systems based on  amorphous silicon photo-diodes  and CCD
detectors are very  commonly used. Two decades ago, a  new type of X-ray
imagers based  on photon counting  instead of charge  integration during
exposure  has  been introduced  for  particle  tracking in  high  energy
physics experiments (Becks  et al., 1997). This  approach called quantum
X-ray imaging  is capable of  discriminating and processing  each single
X-ray photon in addition to counting them. It also offers improved image
quality and noise  subtraction compared to the former  devices (Bérar et
al., 2002) while operating at room temperature. In this so-called hybrid
approach where  analytic electronic  chain is  physically bound  to each
pixel, the sensor material can be  chosen according to the energy of the
X-ray photons  to be  detected and  the electronics  custom-designed for
specific  applications   (Basolo  et  al.,  2008;   Ballabriga  et  al.,
2011).  Sensor  and electronics  are  assembled  using bump-bonding  and
flip-chip  technologies resulting  in  a  hybrid-pixels photon  counting
detector.

.. image:: _static/images/detecteur_pixel.jpg
   :width: 400 px
   :align: center

-------------------------------------------------------------------------------

_`The Nearby Supernova Factory`
===============================

The Nearby  Supernova Factory is an  international collaboration created
in  2000 between  cosmolgy  teams  at the  LBNL  (Berkeley, USA),  LPNHE
(Paris,  France), IPNL  (Lyon,  France), CRAL  (Lyon,  France) and  CPPM
(Marseille, France) in order to improve our understanding of type Ia SNe
as distance  indicators.  In  2010, teams  from Universität  Bonn (Bonn,
Germany), MPA (Munich, Germany) and Tsinghua University (Beijing, China)
joined the project.

.. image:: _static/images/SNfactory.png
   :width: 600 px
   :align: center

_`Observational cosmology with Type Ia SNe`
-------------------------------------------

Thermonuclear supernovæ are used as cosmological probes to constrain the
dark energy equation  of state. During the last decade,  a generation of
surveys  (SNLS,  Essence,  SDSS,...)  has  significantly  increased  the
moderate  to high-redshift  (z  > 0.1)  supernova  sample. However,  the
low-redshift  sample  remained a  limiting  factor  of the  cosmological
analysis using SNe. Several projects  started with the goal of improving
the  current  data  set  in  order  to   act  as  a  lever  arm  of  the
Hubble-Lemaître diagram and  to improve our understanding  of SNe. Among
them, the Nearby SuperNova Factory  project initiated by Saul Perlmutter
(Nobel price 2011).

.. image:: _static/images/suzuki.png
   :width: 400 px
   :align: center

_`SuperNova Integral field spectroscopy`
----------------------------------------

The first  characteristic of  SNfactory, which tells  it apart  from the
other  classic  type  Ia  supernovæ experiments,  is  its  observational
approach based on Integral Field Spectroscopy (IFS). Traditional surveys
are following photometrically the  luminosity evolution of the supernova
as a function of time.  A single spectroscopic measurement usually close
to the maximal luminosity is used  to identify the type of the supernova
and the redshift of the host galaxy.  In SNfactory, the field of view of
the  instrument is  divided into  small spatial  elements (spaxels)  and
provides simultaneously  a spectrum for each  spaxel.  The spectroscopic
field of view covers  the field (sky + galaxy +  supernova) and the flux
of the supernova  is collected. A three dimension (x,y,λ)  data cube can
be  reconstructed.  This  technique allows  accurate spectro-photometry,
while in  traditional spectroscopy the collection  efficiency depends on
the size of the slit (therefore,  on the resolution), and a careful slit
alignment is needed to subtract roughly the host galaxy.

.. image:: _static/images/SNIFS.png
   :width: 600 px
   :align: center