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DOE OSTI2025

The Mu2e straw tracker detector status and prototype results

The Mu2e experiment will search for charge-lepton flavor violating (CLFV) muon to electron conversion. It aims to achieve a four-orders of magnitude improvement in sensitivity over previous experiments, allowing it to probe new physics at mass scales up to 10 4 TeV . A precision momentum measurement is needed to resolve the monoenergetic electron that is the signal of CLFV conversion from muon decay-in-orbit backgrounds. Here, this is achieved in Mu2e using a low-mass cylindrical straw tracker operated in vacuum, consisting of 21,000 thin-wall mylar straws held at tension. The Mu2e tracker is now in production and will be completed during 2025. We will discuss the design and status of the experiment and the tracker detector, and show results from data taken with the first tracker module.

Gaseous detector↗

DOE OSTI2024

Analysis and Grading of the Test Performance of PS Modules for the CMS Phase-2 Outer Tracker Upgrade

The Outer Tracker of the CMS experiment provides information about the trajectory of charged particles produced in proton-proton collisions at the LHC. During the High Luminosity LHC upgrade, scheduled for the late 2020s, the Outer Tracker will be replaced with new modules capable of transmitting data to the L1 Trigger. These modules are being assembled at several facilities around the world, including Fermilab, necessitating coordinated standards of module quality. Here I discuss the development of POTATO (Phase-2 Outer Tracker Analyzer of Test Outputs), a C++ software which provides a standardized procedure for analyzing and grading test results of the Outer Tracker modules. The particular focus of this poster is on the analysis and grading of the PS (pixel-strip) modules in POTATO.

Riggall, Caroline↗

DOE OSTI2024

Analysis and Grading of the Test Performance of PS Modules for the CMS Phase-II Outer Tracker Upgrade

The Outer Tracker detector of the Compact Muon Solenoid (CMS) experiment provides information about the trajectory of charged particles produced in proton-proton collisions at the Large Hadron Collider (LHC). During the High Luminosity LHC upgrade, scheduled for the late 2020s, the Outer Tracker will be replaced with new modules capable of transmitting data to the L1 Trigger. These modules are being assembled at several facilities around the world, including Fermilab, necessitating coordinated standards of module quality. Here I discuss the development of POTATO (Phase-II Outer Tracker Analyzer of Test Outputs), a C++ software which provides a standardized procedure for analyzing and grading test results of the Outer Tracker modules. The particular focus of this paper is on the analysis and grading of the PS (pixel-strip) modules in POTATO.

43 PARTICLE ACCELERATORS↗

DOE OSTI2024

Development of POTATO for 2S Module Grading for the CMS Phase-2 Outer Tracker Upgrade

Due to the High Luminosity-Large Hadron Collider (HL-LHC) upgrade, several detectors of the Compact Muon Solenoid (CMS) will need to be upgraded, specifically the new Outer Tracker detector that will be composed of 13,200 silicon modules. The Outer Tracker features two types of modules; the PS (pixel-strip) and the 2S (strip-strip) modules. With a large influx of production of modules, extensive testing is required to ensure they fulfill the performance requirements. This research introduces POTATO (Phase-II Outer Tracker Analyzer of Test Outputs), a specialized software developed in C++ to analyze, grade, and store results in a centralized database since module data will be collected from various international production facilities. The implementation of POTATO will facilitate the selection of the best performing modules for the Outer Tracker upgrade. This paper is focused on the implementation of the analysis of 2S Module results within POTATO.

43 PARTICLE ACCELERATORS↗

DOE OSTI2025

POTATO: A Unified Assessment System for HL-LHC Outer Tracker Module Productions

The CMS detector s silicon tracker will be replaced in preparation for the upcoming High-Luminosity LHC (HL LHC) upgrade. The inner tracker will include a new pixel detector while the outer tracker (OT) will feature 5,592 pixel strip (PS) and 7,608 strip strip (2S) sensor modules with production distributed across 7 sites worldwide, requiring standardized grading and testing. One testing apparatus the burn-in box replicates the temperature cycling conditions that successful modules must withstand. The Phase-II Outer Tracker Analyzer of Test Outputs (POTATO) standardizes module evaluation and grading among testing sites. Given burn-in box test output, POTATO analyzes the results and assigns a letter grade to a module and its sub-components. POTATO's grading process must adapt to evolving standards for module evaluation; hence, we detail work on POTATO's database and grading functionality that will facilitate the unified assessment of Phase-II OT module assembly and testing worldwide. Once completed, POTATO will allow technicians to interact with a database of all graded modules and efficiently assess the global module assembly effort.

Clark, Olivia J. [U. Tennessee, Knoxville]↗

DOE OSTI2026

Solar-Tracker Diffuse-Response Algorithm for Balancing Energy Gain and Mechanical Wear in Photovoltaic Systems

Single-axis solar tracking maximizes photovoltaic energy production under clear-sky conditions; however, its effectiveness decreases under cloudy and overcast skies, where diffuse irradiance dominates and the optimal module orientation changes. Conventional tracking algorithms either neglect sky conditions or rely on simplified diffuse-response strategies that may trigger frequent tracker repositioning under variable cloud cover, leading to increased mechanical wear with marginal energy gains. This work proposes an enhanced diffuse-response tracking algorithm that explicitly accounts for both the intensity and temporal persistence of cloudiness. By requiring overcast conditions to persist for a minimum duration before reorienting the tracker to a diffuse-stow position, the proposed approach reduces unnecessary movements while preserving the benefits of diffuse-response operation. The algorithm is evaluated through numerical simulations based on historical meteorological data and validated using field measurements on monofacial and bifacial photovoltaic strings. The results show that the proposed strategy reduces excess tracker movement from 114% to 0.16% while maintaining nearly the same energy yield. Compared to a conventional diffuse-response algorithm, the associated energy reduction is minimal (≈0.17%) relative to the ≈0.37% yield gain observed at the studied location. These findings demonstrate that incorporating cloudiness duration enables a practical compromise between energy performance and tracker durability, particularly for monofacial photovoltaic systems.

14 SOLAR ENERGY↗

NASA NTRS1971

Star tracker for the Apollo telescope mount

The star tracker for the Apollo Telescope Mount (ATM) has been designed specifically to meet the requirements of the Skylab vehicle and mission. The functions of the star tracker are presented, as well as descriptions of the optical-mechanical assembly (OMA) and the star tracker electronics (STE). Also included are the electronic and mechanical specifications, interface and operational requirements, support equipment and test requirements, and occultation information. Laboratory functional tests, environmental qualification tests, and life tests have provided a high confidence factor in the performance of the star tracker in the laboratory and on the Skylab mission.

Lee, C. E.↗

NASA NTRS1973

Precision Attitude Determination System (PADS) design and analysis. Two-axis gimbal star tracker

Development of the Precision Attitude Determination System (PADS) focused chiefly on the two-axis gimballed star tracker and electronics design improved from that of Precision Pointing Control System (PPCS), and application of the improved tracker for PADS at geosynchronous altitude. System design, system analysis, software design, and hardware design activities are reported. The system design encompasses the PADS configuration, system performance characteristics, component design summaries, and interface considerations. The PADS design and performance analysis includes error analysis, performance analysis via attitude determination simulation, and star tracker servo design analysis. The design of the star tracker and electronics are discussed. Sensor electronics schematics are included. A detailed characterization of the application software algorithms and computer requirements is provided.

Source record↗

NASA NTRS1972

Precision Pointing Control System (PPCS) star tracker test

Tests performed on the TRW precision star tracker are described. The unit tested was a two-axis gimballed star tracker designed to provide star LOS data to an accuracy of 1 to 2 sec. The tracker features a unique bearing system and utilizes thermal and mechanical symmetry techniques to achieve high precision which can be demonstrated in a one g environment. The test program included a laboratory evaluation of tracker functional operation, sensitivity, repeatibility, and thermal stability.

Source record↗

NASA NTRS1974

Precision Attitude Determination System (PADS) system design and analysis: Single-axis gimbal star tracker

The feasibility is evaluated of an evolutionary development for use of a single-axis gimbal star tracker from prior two-axis gimbal star tracker based system applications. Detailed evaluation of the star tracker gimbal encoder is considered. A brief system description is given including the aspects of tracker evolution and encoder evaluation. System analysis includes evaluation of star availability and mounting constraints for the geosynchronous orbit application, and a covariance simulation analysis to evaluate performance potential. Star availability and covariance analysis digital computer programs are included.

Source record↗

NASA NTRS1986

ASTROS - High-performance CCD tracker for spacecraft

The architecture, capabilities, and testing of the Advanced Star and Target Reference Optical Sensor (ASTROS) I and II are described. The ASTROS I tracker is to be utilized for a UV telescope experiment on a Shuttle flight and is capable of measuring pointing errors of 1.5 microrad, and the ASTROS II tracker is being developed for the Mariner Mark II spacecraft to perform tracking, guiding, and optical navigation functions. The requirements for the two trackers are compared. Consideration is given to star and target tracking, optical navigation, and mass and power constraints. The compositions of the trackers, in particular the sensor, electrode drives, amplifiers and signal clamp, video signal processor, control and timing generator, memories, microprocessor, and interface, are examined.

Dennison, E. W.↗

NASA NTRS1993

Star tracker operation in a high density proton field

Algorithms that reject transient signals due to proton effects on charge coupled device (CCD) sensors have been implemented in the HDOS ASTRA-l Star Trackers to be flown on the TOPEX mission scheduled for launch in July 1992. A unique technique for simulating a proton-rich environment to test trackers is described, as well as the test results obtained. Solar flares or an orbit that passes through the South Atlantic Anomaly can subject the vehicle to very high proton flux levels. There are three ways in which spurious proton generated signals can impact tracker performance: the many false signals can prevent or extend the time to acquire a star; a proton-generated signal can compromise the accuracy of the star's reported magnitude and position; and the tracked star can be lost, requiring reacquisition. Tests simulating a proton-rich environment were performed on two ASTRA-1 Star Trackers utilizing these new algorithms. There were no false acquisitions, no lost stars, and a significant reduction in reported position errors due to these improvements.

Miklus, Kenneth J.↗

NASA NTRS1992

Performance of the ice motion tracker at the Alaska SAR facility

An ice motion tracker has been implemented as part of the Ice/Ocean Geophysical Processor System (GPS) at the Alaska Synthetic Aperture Radar (SAR) Facility. The motion tracker operates in an unsupervised mode and utilizes a combination of feature-based and area-based matching to construct the displacement field from time-separated SAR imagery. The tracker is used to generate routine motion products for investigations of the kinematics and dynamics of sea ice in the polar regions. A number of filters for elimination of outliers and incorrect matches have been implemented to maintain the quality of the motion vector product. Preliminary evaluation of the tracking algorithm with European Space Agency Remote Sensing Satellite (ERS-1) data indicate that these requirements are satisfied. The performance and shortcomings of the motion tracker are discussed.

Kwok, Ronald↗

NASA NTRS1992

A low-cost, CCD solid state star tracker

Applied Research Corporation (ARC) has developed an engineering model of a multi-star CCD-based tracker for space applications requiring radiation hardness, high reliability and low power consumption. The engineering unit compared favorably in functional performance tests to the standard NASA single-star tracker. Characteristics of the ARC star tracker are: field of view = 10 deg x 7.5 deg, sensitivity range of -1 to +5 star magnitude, NEA = 3 in x 3 in, linearity = 5 in x 5 in, and power consumption of 1-3 W (operating mode dependent). The software is upgradable through a remote link. The hardware-limited acquisition rate is 1-5 Hz for stars of +2 to +5 magnitude and 10-30 Hz for -1 to +2 magnitude stars. Mechanical and electrical interfaces are identical to the standard NASA star tracker.

Chmielowski, M.↗

NASA NTRS1995

Experience from the in-flight calibration of the Extreme Ultraviolet Explorer (EUVE) and Upper Atmosphere Research Satellite (UARS) fixed head star trackers (FHSTs)

Since the original post-launch calibration of the FHSTs (Fixed Head Star Trackers) on EUVE (Extreme Ultraviolet Explorer) and UARS (Upper Atmosphere Research Satellite), the Flight Dynamics task has continued to analyze the FHST performance. The algorithm used for inflight alignment of spacecraft sensors is described and the equations for the errors in the relative alignment for the simple 2 star tracker case are shown. Simulated data and real data are used to compute the covariance of the relative alignment errors. Several methods for correcting the alignment are compared and results analyzed. The specific problems seen on orbit with UARS and EUVE are then discussed. UARS has experienced anomalous tracker performance on an FHST resulting in continuous variation in apparent tracker alignment. On EUVE, the FHST residuals from the attitude determination algorithm showed a dependence on the direction of roll during survey mode. This dependence is traced back to time tagging errors and the original post launch alignment is found to be in error due to the impact of the time tagging errors on the alignment algorithm. The methods used by the FDF (Flight Dynamics Facility) to correct for these problems is described.

Lee, Michael↗

NASA NTRS2001

Spacecraft attitude control systems with dynamic methods and structures for processing star tracker signals

Methods are provided for dynamically processing successively-generated star tracker data frames and associated valid flags to generate processed star tracker signals that have reduced noise and a probability greater than a selected probability P.sub.slctd of being valid. These methods maintain accurate spacecraft attitude control in the presence of spurious inputs (e.g., impinging protons) that corrupt collected charges in spacecraft star trackers. The methods of the invention enhance the probability of generating valid star tracker signals because they respond to a current frame probability P.sub.frm by dynamically selecting the largest valid frame combination whose combination probability P.sub.cmb satisfies a selected probability P.sub.slctd. Noise is thus reduced while the probability of finding a valid frame combination is enhanced. Spacecraft structures are also provided for practicing the methods of the invention.

Liu, Yong↗

NASA NTRS2019

Star Tracker Accuracy Improvement and Optimization for Attitude Measurement in Three-Axis

High precision attitude measurement systems obviate the need for the beacon from the receiver making it possible for the spacecraft to beam a laser communications signal to a ground station without the ground station advertising its location. The research presented targets new detection and estimation methods to improve the accuracy in locating stars on a focal plane detector, and an understanding of the effects of changes in the optics design parameters and aberration, including defocus, on the navigation solution itself. This understanding can lead to an optimization of the attitude solution with respect to those optics realm parameter changes. The methodology discussed includes the development of a model of a current star tracker system. Using this model, multiple algorithms are implemented, including a multi-hypothesis method (MHT), to detect and estimate the position of the stars on the focal plane detector. It will be shown that using the MHT for detection and estimation, a greater accuracy can be found for each star estimation from more traditional detection and estimation algorithms. The approach then uses the model to develop statistics of the star tracker and the attitude estimation outputs to understand the accuracy, or variance, of the system's attitude solution. This solution is repeated for a range of defocus aberration, and a lower limit to the variance of the attitude solution is shown. A Cramer Rao lower bound solution is derived for the star tracker system and the results are compared to the Monte Carlo analysis from the model and shown to correlate very well. The approach uses a star image not as a Gaussian spot on the focal plane as done in previous work, and use of an image that includes the effects of aberrations of the optic system, and the effects of under-sampling and noise from the focal plane detector as well. Analysis includes exploring a star tracker's accuracy improvement through the combination of focus error and under-sampling effects alone, possibly contradicting conventional wisdom and approaches.

Lichter, Michael J.↗

DOE OSTI2025

Operation and performance of the CMS silicon strip tracker with proton-proton collisions at the CERN LHC

Salient aspects of the commissioning, calibration, and performance of the CMS silicon strip tracker are discussed, drawing on experience during operation with proton-proton collisions delivered by the CERN LHC. The data were obtained with a variety of luminosities. The operating temperature of the strip tracker was changed several times during this period and results are shown as a function of temperature in several cases. Details of the system performance are presented, including occupancy, signal-to-noise ratio, Lorentz angle, and single-hit spatial resolution. Saturation effects in the APV25 readout chip preamplifier observed during early Run 2 are presented, showing the effect on various observables and the subsequent remedy. Studies of radiation effects on the strip tracker are presented both for the optical readout links and the silicon sensors. The observed effects are compared to simulation, where available, and they generally agree well with expectations.

47 OTHER INSTRUMENTATION↗