9 research outputs found
Total Ionizing Dose Effects on CMOS Image Sensor for the ULTRASAT Space Mission
ULTRASAT (ULtraviolet TRansient Astronomy SATellite) is a wide-angle space
telescope that will perform deep time-resolved surveys in the near-ultraviolet
spectrum. ULTRASAT is a space mission led by the Weizmann Institute of Science
and the Israel Space Agency and is planned for launch in 2025. The camera
implements backside-illuminated, stitched pixel sensors. The pixel has a
dual-conversion-gain 4T architecture, with a pitch of and is
produced in a process by Tower Semiconductor. Before the final
sensor was available for testing, test sensors provided by Tower were used to
gain first insights into the pixel's radiation tolerance. One of the main
contributions to sensor degradation due to radiation for the ULTRASAT mission
is Total Ionizing Dose (TID). TID measurements on the test sensors have been
performed with a Co-60 gamma source at Helmholz Zentrum Berlin and CC-60
facility at CERN and preliminary results are presented.Comment: Part of the conference: Frontier Detectors for Frontier Physics: 15th
Pisa Meeting on Advanced Detectors, La Biodola - Isola d'Elba Published in:
Nuclear Instruments and Methods in Physics Research Section A: Accelerators,
Spectrometers, Detectors and Associated Equipment Available online 15 June
2023, 168463. In Press, Journal Pre-proo
The Lunar Lander Neutron and Dosimetry (LND) Experiment on Chang'E 4
Chang'E 4 is the first mission to the far side of the Moon and consists of a
lander, a rover, and a relay spacecraft. Lander and rover were launched at
18:23 UTC on December 7, 2018 and landed in the von K\'arm\'an crater at 02:26
UTC on January 3, 2019. Here we describe the Lunar Lander Neutron \& Dosimetry
experiment (LND) which is part of the Chang'E 4 Lander scientific payload. Its
chief scientific goal is to obtain first active dosimetric measurements on the
surface of the Moon. LND also provides observations of fast neutrons which are
a result of the interaction of high-energy particle radiation with the lunar
regolith and of their thermalized counterpart, thermal neutrons, which are a
sensitive indicator of subsurface water content.Comment: 38 pages, submitted to Space Science Review
The scientific payload of the Ultraviolet Transient Astronomy Satellite (ULTRASAT)
The Ultraviolet Transient Astronomy Satellite (ULTRASAT) is a space-borne
near UV telescope with an unprecedented large field of view (200 sq. deg.). The
mission, led by the Weizmann Institute of Science and the Israel Space Agency
in collaboration with DESY (Helmholtz association, Germany) and NASA (USA), is
fully funded and expected to be launched to a geostationary transfer orbit in
Q2/3 of 2025. With a grasp 300 times larger than GALEX, the most sensitive UV
satellite to date, ULTRASAT will revolutionize our understanding of the hot
transient universe, as well as of flaring galactic sources. We describe the
mission payload, the optical design and the choice of materials allowing us to
achieve a point spread function of ~10arcsec across the FoV, and the detector
assembly. We detail the mitigation techniques implemented to suppress
out-of-band flux and reduce stray light, detector properties including measured
quantum efficiency of scout (prototype) detectors, and expected performance
(limiting magnitude) for various objects.Comment: Presented in the SPIE Astronomical Telescopes + Instrumentation 202
Total Ionizing Dose effects on CMOS image sensor for the ULTRASAT space mission
ULTRASAT (ULtraviolet TRansient Astronomy SATellite) is a wide-angle space telescope that will perform deep time-resolved surveys in the near-ultraviolet spectrum. ULTRASAT is a space mission led by the Weizmann Institute of Science and the Israel Space Agency and is planned for launch in 2025. The camera implements backside-illuminated, stitched pixel sensors. The pixel has a dual-conversion-gain 4T architecture, with a pitch of 9.5 μm and is produced in a 180nm process by Tower Semiconductor. Before the final sensor was available for testing, test sensors provided by Tower were used to gain first insights into the pixel’s radiation tolerance. One of the main contributions to sensor degradation due to radiation for the ULTRASAT mission is Total Ionizing Dose (TID). TID measurements on the test sensors have been performed with a Co-60 gamma source at Helmholz Zentrum Berlin and CC-60 facility at CERN and preliminary results are presented
First measurements of the radiation dose on the lunar surface
Human exploration of the Moon is associated with substantial risks to astronauts from space radiation. On the surface of the Moon, this consists of the chronic exposure to galactic cosmic rays and sporadic solar particle events. The interaction of this radiation field with the lunar soil leads to a third component that consists of neutral particles, i.e., neutrons and gamma radiation. The Lunar Lander Neutrons and Dosimetry experiment aboard China’s Chang’E 4 lander has made the first ever measurements of the radiation exposure to both charged and neutral particles on the lunar surface. We measured an average total absorbed dose rate in silicon of 13.2 ± 1 μGy/hour and a neutral particle dose rate of 3.1 ± 0.5 μGy/hour
Design of the ULTRASAT UV camera
The Ultraviolet Transient Astronomical Satellite (ULTRASAT) is a scientific UV space telescope that will operate in geostationary orbit. The mission, targeted to launch in 2024, is led by the Weizmann Institute of Science (WIS) in Israel and the Israel Space Agency (ISA). Deutsches Elektronen Synchrotron (DESY) in Germany is tasked with the development of the UV-sensitive camera at the heart of the telescope. The camera's total sensitive area of ≈90mm x 90mm is built up by four back-side illuminated CMOS sensors, which image a field of view of ≈200 deg2. Each sensor has 22:4 megapixels. The Schmidt design of the telescope locates the detector inside the optical path, limiting the overall size of the assembly. As a result, the readout electronics is located in a remote unit outside the telescope. The short focal length of the telescope requires an accurate positioning of the sensors within ±50 μm along the optical axis, with a flatness of ±10 μm. While the telescope will be at around 295K during operations, the sensors are required to be cooled to 200K for dark current reduction. At the same time, the ability to heat the sensors to 343K is required for decontamination. In this paper, we present the preliminary design of the UV sensitive ULTRASAT camera
Radial evolution of the April 2020 stealth coronal mass ejection between 0.8 and 1 AU. Comparison of Forbush decreases at Solar Orbiter and near the Earth
Aims. We present observations of the first coronal mass ejection (CME)
observed at the Solar Orbiter spacecraft on April 19, 2020, and the associated
Forbush decrease (FD) measured by its High Energy Telescope (HET). This CME is
a multispacecraft event also seen near Earth the next day. Methods. We
highlight the capabilities of HET for observing small short-term variations of
the galactic cosmic ray count rate using its single detector counters. The
analytical ForbMod model is applied to the FD measurements to reproduce the
Forbush decrease at both locations. Input parameters for the model are derived
from both in situ and remote-sensing observations of the CME. Results. The very
slow (~350 km/s) stealth CME caused a FD with an amplitude of 3 % in the
low-energy cosmic ray measurements at HET and 2 % in a comparable channel of
the Cosmic Ray Telescope for the Effects of Radiation (CRaTER) on the Lunar
Reconnaissance Orbiter, as well as a 1 % decrease in neutron monitor
measurements. Significant differences are observed in the expansion behavior of
the CME at different locations, which may be related to influence of the
following high speed solar wind stream. Under certain assumptions, ForbMod is
able to reproduce the observed FDs in low-energy cosmic ray measurements from
HET as well as CRaTER, but with the same input parameters, the results do not
agree with the FD amplitudes at higher energies measured by neutron monitors on
Earth. We study these discrepancies and provide possible explanations.
Conclusions. This study highlights that the novel measurements of the Solar
Orbiter can be coordinated with other spacecraft to improve our understanding
of space weather in the inner heliosphere. Multi-spacecraft observations
combined with data-based modeling are also essential to understand the
propagation and evolution of CMEs as well as their space weather impacts.Comment: accepted for publication in Astronomy & Astrophysic