Next generation, space-based, Sun-Earth System remote sensing missions place severe challenges on focal plane technologies to achieve their science goals. Among these are high sensitivity over a broad spectral range, small pixel size, fast readout, radiation tolerance, low power consumption, photometric accuracy & stability, and scalable mosaic technology for constructing large focal plane mosaics. Our Jet Propulsion Laboratory, Lawrence Berkeley National Laboratory, University of Alabama in Huntsville collaboration has begun the development of an Advanced Broadband Imager (ABI) to address these challenges for future Sun Solar System Connection science missions. We describe here the development of the delta-doped, high-purity, p channel charge coupled devices, which form the heart of the ABI imager, and our plans for future development. The current technical readiness levels of ABI component technologies are TRL 2 to TRL 4. Our proposed development program envisions achieving TRL 5 within 3 years with flight validation in the context of an Earth Sun System Science mission occurring within 6 years via the Quiet-Sun Transition Region Explorer EUV Telescope (Q-STREET) rocket-borne observatory.
We present new characterization results for a large format, 15 um pixel pitch, 2kx4k format, p-channel CCD fabricated on high resistivity silicon at Lawrence Berkeley National Laboratory. The fully-depleted device is 300 um thick and backside illuminated utilizing 4-side buttable packaging. We report on measurements of standard operating characteristics including charge transfer efficiency, readout noise, cosmetics performance, dark current, and well depth. We have also made preliminary measurements of the device's X-Ray energy resolution and tests of device linearity.
Anne Ealet, Eric Prieto, Alain Bonissent, Roger Malina, Gérard Smadja, A. Tilquin, Gary Bernstein, Stephane Basa, D. Fouchez, Olivier Le Fevre, Alain Mazure, Greg Aldering, R. Amanullah, Pierre Astier, E. Barrelet, Christopher Bebek, Lars Bergstrom, Manfred Bester, Roger Blandford, Ralph Bohlin, Charles Bower, Mark Brown, Myron Campbell, William Carithers, Eugene Commins, W. Craig, C. Day, F. DeJongh, Susana Deustua, H. Diehl, S. Dodelson, Richard Ellis, M. Emmet, Josh Frieman, Andrew Fruchter, D. Gerdes, L. Gladney, Gerson Goldhaber, Ariel Goobar, Donald Groom, Henry Heetderks, M. Hoff, Stephen Holland, M. Huffer, L. Hui, Dragan Huterer, B. Jain, Patrick Jelinsky, Armin Karcher, Steven Kent, Steven Kahn, Alex Kim, William Kolbe, B. Krieger, G. Kushner, N. Kuznetsova, Robin Lafever, J. Lamoureux, Michael Lampton, Michael Levi, P. Limon, Huan Lin, Eric Linder, Stewart Loken, W. Lorenzon, J. Marriner, P. Marshall, R. Massey, Timothy McKay, Shawn McKee, Ramon Miquel, Nicholas Morgan, E. Mörtsell, Nick Mostek, Stuart Mufson, J. Musser, Peter Nugent, Hakeem Oluseyi, Reynald Pain, Nick Palaio, David Pankow, John Peoples, Saul Perlmutter, David Rabinowitz, Alexandre Refregier, Jason Rhodes, Natalie Roe, D. Rusin, V. Scarpine, Michael Schubnell, Michael Sholl, Roger Smith, George Smoot, Jeffrey Snyder, Anthony Spadafora, A. Stebbins, Christopher Stoughton, Andrew Szymkowiak, Gregory Tarlé, Keith Taylor, Andrew Tomasch, Douglas Tucker, Henrik von der Lippe, D. Vincent, Jean-Pierre Walder, Guobin Wang, W. Wester
A well-adapted spectrograph concept has been developed for the SNAP (SuperNova/Acceleration Probe) experiment. The goal is to ensure proper identification of Type Iz supernovae and to standardize the magnitude of each candidate by determining explosion parameters. The spectrograph is also a key element for the calibration of the science mission. An instrument based on an integral field method with the powerful concept of imager slicing has been designed and is presented in this paper. The spectrograph concept is optimized to have high efficiency and low spectral resolution (R~100), constant through the wavelength range (0.35-1.7μm), adapted to the scientific goals of the mission.
Michael Sholl, Michael Lampton, Greg Aldering, W. Althouse, R. Amanullah, James Annis, Pierre Astier, Charles Baltay, E. Barrelet, Stephane Basa, Christopher Bebek, Lars Bergstrom, Gary Bernstein, Manfred Bester, Bruce Bigelow, Roger Blandford, Ralph Bohlin, Alain Bonissent, Charles Bower, Mark Brown, Myron Campbell, William Carithers, Eugene Commins, W. Craig, C. Day, F. DeJongh, Susana Deustua, T. Diehl, S. Dodelson, Anne Ealet, Richard Ellis, W. Emmet, D. Fouchez, Josh Frieman, Andrew Fruchter, D. Gerdes, L. Gladney, Gerson Goldhaber, Ariel Goobar, Donald Groom, Henry Heetderks, M. Hoff, Stephen Holland, M. Huffer, L. Hui, Dragan Huterer, B. Jain, Patrick Jelinsky, Armin Karcher, Steven Kahn, Steven Kent, Alex Kim, William Kolbe, B. Krieger, G. Kushner, N. Kuznetsova, Robin Lafever, J. Lamoureux, Olivier Le Fevre, Michael Levi, P. Limon, Huan Lin, Eric Linder, Stewart Loken, W. Lorenzon, Roger Malina, J. Marriner, P. Marshall, R. Massey, Alain Mazure, Timothy McKay, Shawn McKee, Ramon Miquel, Nicholas Morgan, E. Mörtsell, Nick Mostek, Stuart Mufson, J. Musser, Peter Nugent, Hakeem Oluseyi, Reynald Pain, Nick Palaio, David Pankow, John Peoples, Saul Perlmutter, Eric Prieto, David Rabinowitz, Alexandre Refregier, Jason Rhodes, Natalie Roe, D. Rusin, V. Scarpine, Michael Schubnell, Gérard Smadja, Roger Smith, George Smoot, Jeffrey Snyder, Anthony Spadafora, A. Stebbins, Christopher Stoughton, Andrew Szymkowiak, Gregory Tarlé, Keith Taylor, A. Tilquin, Andrew Tomasch, Douglas Tucker, D. Vincent, Henrik von der Lippe, Jean-Pierre Walder, Guobin Wang, W. Wester
Mission requirements, the baseline design, and optical systems budgets for the SuperNova/Acceleration Probe (SNAP) telescope are presented. SNAP is a proposed space-based experiment designed to study dark energy and alternate explanations of the acceleration of the universe’s expansion by performing a series of complementary systematics-controlled astrophysical measurements. The goals of the mission are a Type Ia supernova Hubble diagram and a wide-field weak gravitational lensing survey. A 2m widefield three-mirror telescope feeds a focal plane consisting of 36 CCDs and 36 HgCdTe detectors and a high-efficiency, low resolution integral field spectrograph. Details of the maturing optical system, with emphasis on structural stability during terrestrial testing as well as expected environments during operations at L2 are discussed. The overall stray light mitigation system, including illuminated surfaces and visible objects are also presented.
We have developed a precision, 4-side buttable CCD package for 2kx2k and 2kx4k format devices with minimal mechanical stress on the CCD, excellent thermal properties, reliable electrical connectivity, and shim-free mounting. We report on the package design, assembly and quality assurance procedures, measurements of packaged device flatness and flatness excursions when cooled from room temperature to 140 K, package performance and plans for future development.
Michael Lampton, Michael Sholl, Michael Krim, R. Besuner, Carl Akerlof, Greg Aldering, R. Amanullah, Pierre Astier, Charles Baltay, E. Barrelet, Stephane Basa, Christopher Bebek, John Bercovitz, Lars Bergstrom, Gary Berstein, Manfred Bester, Ralph Bohlin, Alain Bonissent, Charles Bower, Myron Campbell, William Carithers, Eugene Commins, C. Day, Susana Deustua, Richard DiGennaro, Anne Ealet, Richard Ellis, William Emmett, Mikael Eriksson, D. Fouchez, Andrew Fruchter, Jean-Francois Genat, Gerson Goldhaber, Ariel Goobar, Donald Groom, Henry Heetderks, Stephen Holland, Dragan Huterer, William Johnston, Richard Kadel, Armin Karcher, Alex Kim, William Kolbe, Robin Lafever, J. Lamoureux, Oliver LeFevre, Michael Levi, Daniel Levin, Eric Linder, Stewart Loken, Roger Malina, Alain Mazure, Timothy McKay, Shawn McKee, Ramon Miquel, Nicholas Morgan, E. Mortsell, Nick Mostek, Stuart Mufson, J. Musser, Peter Nugent, Hakeem Oluseyi, Reynald Pain, Nick Palaio, David Pankow, Saul Perlmutter, Eric Prieto, David Rabinowitz, Alexandre Refregier, Jason Rhodes, Natalie Roe, Michael Schubnell, G. Smadja, R. Smith, George Smoot, Jeffrey Snyder, Anthony Spadafora, Andrew Szymkowiak, Gregory Tarle, Keith Taylor, A. Tilquin, Andrew Tomasch, D. Vincent, Henrik von der Lippe, Jean-Pierre Walder, Guobin Wang
We present the baseline telescope design for the telescope for the SuperNova/Acceleration Probe (SNAP) space mission. SNAP’s purpose is to determine expansion history of the Universe by measuring the redshifts, magnitudes, and spectral classifications of thousands of supernovae with unprecedented accuracy. Discovering and measuring these supernovae demand both a wide optical field and a high sensitivity throughout the visible and near IR wavebands. We have adopted the annular-field three-mirror anastigmat (TMA) telescope configuration, whose classical aberrations (including chromatic) are zero. We show a preliminary optmechanical design that includes important features for stray light control and on-orbit adjustment and alignment of the optics. We briefly discuss stray light and tolerance issues, and present a preliminary wavefront error budget for the SNAP Telescope. We conclude by describing some of the design tasks being carried out during the current SNAP research and development phase.
An overview of CCD development efforts at Lawrence Berkeley National
Laboratory is presented. Operation of fully-depleted, back-illuminated CCD's fabricated on high resistivity silicon is described, along with results on the use of such CCD's at ground-based observatories. Radiation damage and point-spread function measurements are described, as well as discussion of CCD fabrication technologies.
Christopher Bebek, Carl Akerlof, Greg Aldering, R. Amanullah, Pierre Astier, Charles Baltay, E. Barrelet, Stephane Basa, John Bercovitz, Lars Bergstrom, Gary Berstein, Manfred Bester, Ralph Bohlin, Alain Bonissent, Charles Bower, Myron Campbell, William Carithers, Eugene Commins, C. Day, Susana Deustua, Richard DiGennaro, Anne Ealet, Richard Ellis, William Emmett, Mikael Eriksson, D. Fouchez, Andrew Fruchter, Jean-Francois Genat, Gerson Goldhaber, Ariel Goobar, Donald Groom, Henry Heetderks, Stephen Holland, Dragan Huterer, William Johnston, Richard Kadel, Armin Karcher, Alex Kim, William Kolbe, Robin Lafever, J. Lamoureux, Michael Lampton, Oliver LeFevre, Michael Levi, Daniel Levin, Eric Linder, Stewart Loken, Roger Malina, Alain Mazure, Timothy McKay, Shawn McKee, Ramon Miquel, Nicholas Morgan, E. Mortsell, N. Mostek, Stuart Mufson, J. Musser, Natalie Roe, Peter Nugent, Hakeem Oluseyi, Reynald Pain, Nicholas Palaio, David Pankow, Saul Perlmutter, Eric Prieto, David Rabinowitz, Alexandre Refregier, Jason Rhodes, Michael Schubnell, Michael Sholl, G. Smadja, R. Smith, George Smoot, Jeffrey Snyder, Anthony Spadafora, Andrew Szymkowiak, Gregory Tarle, Keith Taylor, A. Tilquin, Andrew Tomasch, D. Vincent, Henrik von der Lippe, Jean-Pierre Walder, Guobin Wang
The proposed SuperNova/Acceleration Probe (SNAP) mission will have a two-meter class telescope delivering diffraction-limited images to an instrumented 0.7 square degree field in the visible and near-infrared wavelength regime. The requirements for the instrument suite and the present configuration of the focal plane concept are presented. A two year R&D phase, largely supported by the Department of Energy, is just beginning. We describe the development activities that are taking place to advance our preparedness for mission proposal in the areas of detectors and electronics.
Gregory Tarle, Carl Akerlof, Greg Aldering, R. Amanullah, Pierre Astier, E. Barrelet, Christopher Bebek, Lars Bergstrom, John Bercovitz, Gary Bernstein, Manfred Bester, Alain Bonissent, C. Bower, Mark Brown, William Carithers, Eugene Commins, C. Day, Susana Deustua, Richard DiGennaro, Anne Ealet, Richard Ellis, Mikael Eriksson, Andrew Fruchter, Jean-Francois Genat, Gerson Goldhaber, Ariel Goobar, Donald Groom, Stewart Harris, Peter Harvey, Henry Heetderks, Steven Holland, Dragan Huterer, Armin Karcher, Alex Kim, William Kolbe, B. Krieger, R. Lafever, J. Lamoureux, Michael Lampton, Michael Levi, Daniel Levin, Eric Linder, Stewart Loken, Roger Malina, R. Massey, Ramon Miquel, Timothy McKay, Shawn McKee, E. Moertsell, N. Mostek, Stuart Mufson, J. Musser, Peter Nugent, Hakeem Oluseyi, Reynald Pain, Nicholas Palaio, David Pankow, Saul Perlmutter, R. Pratt, Eric Prieto, Alexandre Refregier, Jason Rhodes, Kem Robinson, N. Roe, Michael Schubnell, Michael Sholl, G. Smadja, George Smoot, Anthony Spadafora, Andrew Tomasch, D. Vincent, H. von der Lippe, J.-P. Walder, Guobin Wang
The SuperNova/Acceleration Probe (SNAP) will measure precisely the cosmological expansion history over both the acceleration and deceleration epochs and thereby constrain the nature of the dark energy that dominates our universe today. The SNAP focal plane contains equal areas of optical CCDs and NIR sensors and an integral field spectrograph. Having over 150 million pixels and a field-of-view of 0.34 square degrees, the SNAP NIR system will be the largest yet constructed. With sensitivity in the range 0.9-1.7 μm, it will detect Type Ia supernovae between z = 1 and 1.7 and will provide follow-up precision photometry for all supernovae. HgCdTe technology, with a cut-off tuned to 1.7 μm, will permit passive cooling at 140 K while maintaining noise below zodiacal levels. By dithering to remove the effects of intrapixel variations and by careful attention to other instrumental effects, we expect to control relative photometric accuracy below a few hundredths of a magnitude. Because SNAP continuously revisits the same fields we will be able to achieve outstanding statistical precision on the photometry of reference stars in these fields, allowing precise monitoring of our detectors. The capabilities of the NIR system for broadening the science reach of SNAP are discussed.
Anne Ealet, Eric Prieto, Alain Bonissent, Roger Malina, G. Bernstein, Stephane Basa, Oliver LeFevre, Alain Mazure, Christophe Bonneville, Carl Akerlof, Greg Aldering, R. Amanullah, Pierre Astier, E. Barrelet, Christopher Bebek, Lars Bergstrom, John Bercovitz, Manfred Bester, C. Bower, William Carithers, Eugene Commins, C. Day, Susana Deustua, Richard DiGennaro, R. Ellis, Mikael Eriksson, Andrew Fruchter, Jean-Francois Genat, Gerson Goldhaber, Ariel Goobar, Donald Groom, Stewart Harris, Peter Harvey, Henry Heetderks, Steven Holland, Dragan Huterer, Armin Karcher, Alex Kim, William Kolbe, B. Krieger, R. Lafever, J. Lamoureux, Michael Lampton, Michael Levi, Daniel Levin, Eric Linder, Stewart Loken, R. Massey, Timothy McKay, Shawn McKee, Ramon Miquel, E. Moertsell, N. Mostek, Stuart Mufson, J. Musser, Peter Nugent, Hakeem Oluseyi, Reynald Pain, Nicholas Palaio, David Pankow, Saul Perlmutter, R. Pratt, Alexandre Refregier, J. Rhodes, Kem Robinson, N. Roe, Michael Sholl, Michael Schubnell, G. Smadja, George Smoot, Anthony Spadafora, Gregory Tarle, Andrew Tomasch, H. von der Lippe, D. Vincent, J.-P. Walder, Guobin Wang
A well-adapted spectrograph concept has been developed for the SNAP (SuperNova/Acceleration Probe) experiment. The goal is to ensure proper identification of Type Ia supernovae and to standardize the magnitude of each candidate by determining explosion parameters. An instrument based on an integral field method with the powerful concept of imager slicing has been designed and is presented in this paper. The spectrograph concept is optimized to have very high efficiency and low spectral resolution (R~100), constant through the wavelength range (0.35-1.7μm), adapted to the scientific goals of the mission.
Michael Lampton, Christopher Bebek, Carl Akerlof, Greg Aldering, R. Amanullah, Pierre Astier, E. Barrelet, Lars Bergstrom, John Bercovitz, Gary Bernstein, Manfred Bester, Alain Bonissent, C. Bower, William Carithers, Eugene Commins, C. Day, Susana Deustua, Richard DiGennaro, Anne Ealet, Richard Ellis, Mikael Eriksson, Andrew Fruchter, Jean-Francois Genat, Gerson Goldhaber, Ariel Goobar, Donald Groom, Stewart Harris, Peter Harvey, Henry Heetderks, Steven Holland, Dragan Huterer, Armin Karcher, Alex Kim, William Kolbe, B. Krieger, R. Lafever, J. Lamoureux, Michael Levi, Daniel Levin, Eric Linder, Stewart Loken, Roger Malina, R. Massey, Timothy McKay, Steven McKee, Ramon Miquel, E. Moertsell, N. Mostek, Stuart Mufson, J. Musser, Peter Nugent, Hakeem Oluseyi, Reynald Pain, Nicholas Palaio, David Pankow, Saul Perlmutter, R. Pratt, Eric Prieto, Alexandre Refregier, J. Rhodes, Kem Robinson, N. Roe, Michael Sholl, Michael Schubnell, G. Smadja, George Smoot, Anthony Spadafora, Gregory Tarle, Andrew Tomasch, H. von der Lippe, D. Vincent, J.-P. Walder, Guobin Wang
The proposed SuperNova/Acceleration Probe (SNAP) mission will have a two-meter class telescope delivering diffraction-limited images to an instrumented 0.7 square-degree field sensitive in the visible and near-infrared wavelength regime. We describe the requirements for the instrument suite and the evolution of the focal plane design to the present concept in which all the instrumentation -- visible and near-infrared imagers, spectrograph, and star guiders -- share one common focal plane.
Alex Kim, Carl Akerlof, Greg Aldering, R. Amanullah, Pierre Astier, E. Barrelet, Christopher Bebek, Lars Bergstrom, J. Bercovitz, Gary Bernstein, M. Bester, A. Bonissent, C. Bower, William Carithers, Eugene Commins, C. Day, Susana Deustua, R. DiGennaro, A. Ealet, Richard Ellis, M. Eriksson, Andrew Fruchter, Jean-Francois Genat, Gerson Goldhaber, Ariel Goobar, Donald Groom, Stewart Harris, Peter Harvey, Henry Heetderks, Steven Holland, Dragan Huterer, Armin Karcher, William Kolbe, B. Krieger, Robin Lafever, J. Lamoureux, Michael Lampton, Michael Levi, Daniel Levin, Eric Linder, Stewart Loken, Roger Malina, R. Massey, Timothy McKay, Shawn McKee, Ramon Miquel, E. Mortsell, N. Mostek, Stuart Mufson, J. Musser, Peter Nugent, Hakeem Oluseyi, Reynald Pain, Nicholas Palaio, David Pankow, Saul Perlmutter, R. Pratt, Eric Prieto, Alexandre Refregier, Jason Rhodes, Kem Robinson, N. Roe, Michael Sholl, Michael Schubnell, G. Smadja, George Smoot, Anthony Spadafora, Gregory Tarle, Andrew Tomasch, H. von der Lippe, D. Vincent, J.-P. Walder, Guobin Wang
The Supernova / Acceleration Probe (SNAP) is a proposed space-borne observatory that will survey the sky with a wide-field optical/near-infrared (NIR) imager. The images produced by SNAP will have an unprecedented combination of depth, solid-angle, angular resolution, and temporal sampling. For 16 months each, two 7.5 square-degree fields will be observed every four days to a magnitude depth of AB=27.7 in each of the SNAP filters, spanning 3500-17000Å. Co-adding images over all epochs will give AB=30.3 per filter. In addition, a 300 square-degree field will be surveyed to AB=28 per filter, with no repeated temporal sampling. Although the survey strategy is tailored for supernova and weak gravitational lensing observations, the resulting data will support a broad range of auxiliary science programs.
Michael Lampton, Carl Akerlof, Greg Aldering, R. Amanullah, Pierre Astier, E. Barrelet, Christopher Bebek, Lars Bergstrom, John Bercovitz, G. Bernstein, Manfred Bester, Alain Bonissent, C. Bower, William Carithers, Eugene Commins, C. Day, Susana Deustua, Richard DiGennaro, Anne Ealet, Richard Ellis, Mikael Eriksson, Andrew Fruchter, Jean-Francois Genat, Gerson Goldhaber, Ariel Goobar, Donald Groom, Stewart Harris, Peter Harvey, Henry Heetderks, Steven Holland, Dragan Huterer, Armin Karcher, Alex Kim, William Kolbe, B. Krieger, R. Lafever, J. Lamoureux, Michael Levi, Daniel Levin, Eric Linder, Stewart Loken, Roger Malina, R. Massey, Timothy McKay, Shawn McKee, Ramon Miquel, E. Mortsell, N. Mostek, Stuart Mufson, J. Musser, Peter Nugent, Hakeem Oluseyi, Reynald Pain, Nicholas Palaio, David Pankow, Saul Perlmutter, R. Pratt, Eric Prieto, Alexandre Refregier, J. Rhodes, Kem Robinson, N. Roe, Michael Sholl, Michael Schubnell, G. Smadja, George Smoot, A. Spadafora, Gregory Tarle, Andrew Tomasch, H. von der Lippe, R. Vincent, J.-P. Walder, Guobin Wang
The SuperNova/Acceleration Probe (SNAP) mission will require a two-meter class telescope delivering diffraction limited images spanning a one degree field in the visible and near infrared wavelength regime. This requirement, equivalent to nearly one billion pixel resolution, places stringent demands on its optical system in terms of field flatness, image quality, and freedom from chromatic aberration. We discuss the advantages of annular-field three-mirror anastigmat (TMA) telescopes for applications such as SNAP, and describe the features of the specific optical configuration that we have baselined for the SNAP mission. We discuss the mechanical design and choice of materials for the telescope. Then we present detailed ray traces and diffraction calculations for our baseline optical design. We briefly discuss stray light and tolerance issues, and present a preliminary wavefront error budget for the SNAP Telescope. We conclude by describing some of tasks to be carried out during the upcoming SNAP research and development phase.
Greg Aldering, Carl Akerlof, R. Amanullah, Pierre Astier, E. Barrelet, Christopher Bebek, Lars Bergstrom, John Bercovitz, Gary Bernstein, Manfred Bester, Alain Bonissent, Charles Bower, William Carithers, Eugene Commins, C. Day, Susana Deustua, Richard DiGennaro, Anne Ealet, Richard Ellis, Mikael Eriksson, Andrew Fruchter, Jean-Francois Genat, Gerson Goldhaber, Ariel Goobar, Donald Groom, Stewart Harris, Peter Harvey, Henry Heetderks, Steven Holland, Dragan Huterer, Armin Karcher, Alex Kim, William Kolbe, B. Krieger, R. Lafever, James Lamoreux, Michael Lampton, Michael Levi, Daniel Levin, Eric Linder, Stewart Loken, Roger Malina, R. Massey, Timothy McKay, Shawn McKee, Ramon Miquel, E. Moertsell, N. Mostek, Stuart Mufson, J. Musser, Peter Nugent, Hakeem Oluseyi, Reynald Pain, Nicholas Palaio, David Pankow, Saul Perlmutter, R. Pratt, Eric Prieto, Alexandre Refregier, J. Rhodes, Kem Robinson, N. Roe, Michael Sholl, Michael Schubnell, G. Smadja, George Smoot, Anthony Spadafora, Gregory Tarle, Andrew Tomasch, H. von der Lippe, D. Vincent, J.-P. Walder, Guobin Wang
The SuperNova / Acceleration Probe (SNAP) is a space-based experiment to measure the expansion history of the Universe and study both its dark energy and the dark matter. The experiment is motivated by the startling discovery that the expansion of the Universe is accelerating. A 0.7~square-degree imager comprised of 36 large format fully-depleted n-type CCD's sharing a focal plane with 36 HgCdTe detectors forms the heart of SNAP, allowing discovery and lightcurve measurements simultaneously for many supernovae. The imager and a high-efficiency low-resolution integral field spectrograph are coupled to a 2-m three mirror anastigmat wide-field telescope, which will be placed in a high-earth orbit. The SNAP mission can obtain high-signal-to-noise calibrated light-curves and spectra for over 2000 Type Ia supernovae at redshifts between z = 0.1 and 1.7. The resulting data set can not only determine the amount of dark energy with high precision, but test the nature of the dark energy by examining its equation of state. In particular, dark energy due to a cosmological constant can be differentiated from alternatives such as "quintessence", by measuring the dark energy's equation of state to an accuracy of ± 0.05, and by studying its time dependence.
The large imaging format, high sensitivity, compact size, and ease of operation of silicon-based sensors have led instrument designers to choose them for most visible-light imagers and spectrometers for space-based applications. This will probably remain the case in the near future. In fact, technologies presently under development will tend to strengthen the position of the silicon-based sensors. CCD-CMOS hybrids currently being developed may combine the advantages of both imagers and new high-gain amplifiers and could permit photon- counting sensitivity even in large-format imagers. Back- illumination potentially enables silicon detectors to be used for photometry and imaging applications for which front- illuminated devices are poorly suited. Successful detection by back illumination requires treatment of the back surface using techniques such as delta doping. Delta-doped CCDs were developed at the Microdevices Laboratory at the Jet Propulsion Laboratory in 1992. Using molecular beam epitaxy, fully- processed thinned CCDs are modified for UV enhancement by growing 2.5 nm of boron-doped silicon on the back surface. Named delta-doped CCDs because of the sharply-spiked dopant profile in the thin epitaxial layer, these devices exhibit stable and uniform 100% internal quantum efficiency without hysteresis in the visible and ultraviolet regions of the spectrum. In this paper we will discuss the performance of delta-doped CCDs in UV and EUV, applicability to electron- bombarded CCD (EBCCD), our in-house thinning capability, and bonding approaches for producing flat focal plane arrays. Recent activities on the extension of delta-doping to other imaging technologies will also be presented.
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