Date/Time: Thu Jun 05 2025 at 13:00<br/><br/>Location: ISAC Conference Room<br/><br/>Speaker: Guy Leckenby (LP2i Bordeaux)<br/><br/>Title: Surrogate reactions for astrophysics and applications: a comparison at TRIUMF and GSI<br/><br/>Abstract: Join Zoom Meeting
https://uvic.zoom.us/j/89203042744?pwd=LEplQ0Ugb7p6B00WI2XRNke8OQXgaO.1
Meeting ID: 892 0304 2744
Password: 174250
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Neutron-induced reaction cross sections of short-lived nuclei are essential in nuclear astrophysics and for applications in nuclear technology. However, these cross sections are very difficult or impossible to measure due to the difficulty of producing and handling the necessary radioactive targets. The surrogate reaction method is a well established technique that uses an alternative, more-manageable nuclear reaction to create the same compound nucleus as the neutron-induced reaction. The measured de-excitation probabilities of the compound nucleus through the available channels provides experimental information on the fundamental properties of the nucleus, including the fission barrier, gamma-ray strength function, and the nuclear level density, that can then be used to indirectly constrain the neutron-induced cross sections.
In this talk, I will present a comparative look at new surrogate reaction campaigns with radioactive beams in inverse kinematics at both TIGRESS at TRIUMF and the Experimental Storage Ring at GSI. The surrogate method at TRIUMF uses gamam-ray coincidences to identify the gamma emission de-excitation probability, which comes with the usual challenges of gamma-ray efficiency and solid target backgrounds. The requirement of collector states with which to tag the compound nucleus also restricts the method to even-even nuclei. In contrast, the surrogate method at GSI is conducted in the storage ring where the recoiling nucleus can be measured with up to 100% efficiency, allowing us to measure fission, gamma-ray, neutron and even two- and three-neutron emission probabilities simultaneously. The use of the storage ring also allows for a wider range of beams to be studied, albeit with the usual challenges of in-flight purification.<br/><br/>.<br/><br/>______________________________<br/><br/>Detailed information available can be found at <a href='https://www.triumf.ca/research-program/lectures-conferences/upcoming-seminars-lectures'>https://www.triumf.ca/research-program/lectures-conferences/upcoming-seminars-lectures</a> <br/><br/>Date/Time: Thu Jun 05 2025 at 14:00<br/><br/>Location: Auditorium<br/><br/>Speaker: Adam Powell (CERN)<br/><br/>Title: [Quantum Forum Seminar] Observation of the Effect of Gravity on Antimatter and the Future of the ALPHA-g Experiment<br/><br/>Abstract: https://ubc.zoom.us/j/68226245065?pwd=HWgfHU9EBTkdWjaYUadaNoGhoi3XD8.1
Meeting ID: 682 2624 5065
Passcode: 344808
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The antihydrogen laser physics apparatus (ALPHA) collaboration has studied trapped antihydrogen atoms through spectroscopy for several years. In 2023 the collaboration published the first results from a new apparatus, ALPHA-g [1]. By the slow release of magnetically confined antihydrogen, we determine the local gravitational acceleration of antihydrogen is directed towards the Earth and has magnitude, a_gbar =0.75 +/- 0.13 (statistical+systematic) +/- 0.16 (simulation)g, where g = 9.81 ms^(-2).
I will show the experimental details of this first observation of the effect of gravity on antimatter and the systematic studies involved. I will summaries the imminent plans with the ALPHA-g experiment and finally discuss longer term measurements possible using the apparatus.
[1] Observation of the effect of gravity on the motion of antimatter, E. K. Anderson, C. J. Baker, W. Bertsche, et al, Nature volume 621, pages716?722 (2023).
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Adam Powell is a recent recipient of 2025 CAP DNP Thesis Prize, and currently a CERN Fellow and ALPHA's Technical Coordinator.
<br/><br/>https://ubc.zoom.us/j/68226245065?pwd=HWgfHU9EBTkdWjaYUadaNoGhoi3XD8.1
Meeting ID: 682 2624 5065
Passcode: 344808
<br/><br/>______________________________<br/><br/>Detailed information available can be found at <a href='https://www.triumf.ca/research-program/lectures-conferences/upcoming-seminars-lectures'>https://www.triumf.ca/research-program/lectures-conferences/upcoming-seminars-lectures</a> <br/><br/>