This Major Research Instrumentation (MRI) Program award provides funds to support the acquisition of an instrument with which to measure the amount of Carbon-14 (14C or radiocarbon) in plants, animals and some inorganic samples. Carbon-14 is the unstable isotope of carbon and can be used as a ?radioactive clock? to date a range of samples from the last 40+ thousand years. While radiocarbon dating is the most widely used tool with which to determine rates of change and the timing of events which impacted human history, Carbon-14 locked away in natural archives such as tree-rings also offers important insights into a number of key scientific frontiers. These include: reconstructing past global scale changes in atmospheric and oceanic circulation; predicting and mitigating for technology threatening space weather events; understanding the role of solar forcing on climate and; synchronizing global scale chronologies of human, climate and ecological change through the use of globally detected Carbon-14 marker events. The instrument will be integrated into the teaching, public outreach and research programs of the world?s founding Laboratory of Tree-Ring Research (LTRR), which has interwoven with radiocarbon dating since inception of the technique in the 1960s. This provides unique opportunities to enhance and broaden STEM outreach and teaching by combing these two dating and paleoenvironmental reconstruction methods in new ways to introduce core scientific concepts, tell science stories, and inspire new experimentation and applications at the cutting edge of Carbon-14 analysis. This will be accelerated by the proximity of the instrument to an archive of millions of ready-to-analyze, unique, annual-scale Carbon-14 samples housed in LTRR. The purchase of Ionplus AG?s Mini Carbon Dating System (MICADAS) will maximize throughput of stable, high-precision, small-sample (50?500 microgram) measurements of Carbon-14 for applications that require rapid throughput of thousands of samples, such as consecutive measurements from individual tree-rings. The MICADAS will integrate with an Automated Graphitization Equipment (AGE3) system coupled with an Isotope Ratio Mass Spectrometer (IRMS) to facilitate speedier sample preparation and efficient throughput. Installation in LTRR will provide a service center for a local, national, and international user community by offering tree-ring and radiocarbon-dating solutions under one roof, and creating new onsite and remote training opportunities with converging expertise in tree-ring, schlerochronological, and radiocarbon methods. Starting research foci will; continue in progress work towards an international community effort to rebuild the existing tree-ring based portion of the International Radiocarbon Calibration Curve (required by anyone dating samples using radiocarbon) using single tree-ring samples; work to establish baselines for the periodicity and magnitude of past space-weather extremes which could threaten modern infrastructure; provide an annually resolved proxy record of solar forcing on climate through the Holocene; reveal ?cosmogenic anchor points? to synchronize disparate proxies such as ice-core and tree-ring records; explore global and regional variability in carbon cycling and; assess ocean circulation in critical climatic zones through comparison of Carbon-14 time-series from tree-rings and annually laminated marine bivalves. The facility will respond to an increasing need for niche training in combined applications using tree-ring dating techniques and radiocarbon analysis by offering targeted interdisciplinary training opportunities (locally, nationally and internationally) through a range of workshops, summer schools, scholarship programs and web-resources. The instrument?s accessibility, high capacity and throughput, plus sample preparation requirements will also provide outstanding teaching and training opportunities to benefit undergraduate and graduate STEM students, early-career researchers, and faculty at the University of Arizona (a land-grant, Hispanic Serving Institution with a 52% female student population). Integration of the instrument and associated core scientific concepts into a thriving outreach program, which reaches regional Title 1 schools and serves c. 2,500 visitors a year, will ensure that the new facility not only functions as a nexus to generate new-cross-cutting research applications, but also as a place to inspire the next generation of STEM scientists and to inform the public about the ways science is used to measure time and explore Earth?s past, present and future. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.