the full fiber cable commercially, the project
has been delayed by a few months, but we
should still see on-telescope testing beginning in early 2013 at Gemini North.
Gemini Multi-Object
Spectrograph CCD Upgrade:
In the June 2012 issue of GeminiFocus, we
highlighted our plan to install the new Hamamatsu CCDs into the Gemini Multi-Object
Spectrograph (GMOS) at Gemini North in
January 2013, and subsequent installation
into GMOS at Gemini South in semester
2013B. Given the successful installation of
the deep depletion e2v CCDs into GMOSN in 2011, scientific priorities expressed by
Gemini’s Science and Technology Advisory
Committee and other community members,
and resource conflicts with other projects at
Gemini, we have instead decided to install
the CCDs into GMOS-S first.
Figure 4.
GMOS-CCD metrology
setup at the Hilo Base
Facility lab. This is used to
precisely align the three
new detector chips.
32
Given the current activity at Gemini South
with FLAMINGOS-2, GeMS, and GSAOI, as
well as the expected delivery of GPI in the
southern autumn, the earliest window for
installation into GMOS-S is now around June
2013. Installing within this window, however,
necessitates there being other instruments
GeminiFocus
capable of filling the queue with GMOS off
the telescope. GeMS, GSAOI, FLAMINGOS-2,
and GPI should all be available, but if two or
more of these projects suffer additional setbacks, we may have to delay the GMOS-S CCD
installation until these other instruments become available. Our baseline plan, though, is
to install the CCDs in GMOS-S in the southern
winter, then into GMOS-N in early 2014.
Meanwhile, we believe the hardware signal
filtering mentioned in our last GeminiFocus
article, and implemented by Gemini’s Detector Engineer, Kevin Hanna, has satisfactorily reduced the read noise. We have also
replaced one previously damaged science
CCD. The new CCD comes with an enhanced
coating from Hamamatsu which maintains
the red sensitivity of the other two CCDs
and adds blue sensitivity quite similar to the
current GMOS-S CCDs. This new CCD, therefore, will be placed in the blue-most spectral
position in the array to make maximum use
of its enhanced sensitivity in that part of the
spectrum. Figure 4 shows the setup used at
the Hilo Base Facility to precisely align the
three new CCD chips.
Kevin has also developed an internal electrostatic discharge (ESD) protection circuit
that will fit inside the GMOS
dewar and seat between the
CCDs and the outside world.
ESD consultants have reviewed
and approved this circuit that
will help make the new CCDs
safe for what we hope is a long
life inside the GMOS instruments. Unlike the e2v CCDs
currently in GMOS, these new
Hamamatsu detectors do not
have built-in ESD protection,
and thus, these very sensitive
devices are quite vulnerable
to damage. Once installed,
this circuit should provide the
missing required protection.
December2012