The High Energy Physics group met at Caltech’s Athenaeum with former HEP PI and 2017 Physics Nobel Laureate Barry Barish, to honor him for his award and his legacy in physics
Barry Barish's career spans a wide range of physics experiments, seminal work that helped establish research at the premier DOE National Laboratories (BNL, SLAC and Fermilab), leadership in international experiments and projects, and one of the great discoveries in the past century the detection of gravitational waves. The Enrico Fermi Award recognizes leadership related to science supported by the U.S. Department of Energy. Barry's technical acumen and leadership have enabled the success of projects in the U.S. and abroad which have been directly funded by DOE. Barish influenced progress and direction for D.o.E.'s stewardship of experimental particle physics research. It is unavoidable to recognize that throughout his distinguished scientific career, Barish has also tirelessly devoted his time and energy to the physics community at large. As president of the American Physical Society, member of the National Science Board, and through numerous committees small and large, Barry has served as prime example of leadership to the Department of Energy's and National Science Foundation's domestic and international projects.
Barry Barish started his career as an engineering student at Berkeley, switching to physics during his freshman year. As a beginning grad student at Berkeley, instead of joining Luis Alvarez (who was twisting the arm of the best students to join his radiation lab), he decided he would just go off and do something that hadn't been done, that he wanted to do himself, in the 184 inch Berkeley cyclotron. As a postdoc he partnered with Alvin Tollestrup, a professor at Caltech leading the effort to develop high energy physics in big national facilities such as the Bevatron. Still a young researcher, Barish designed and built the antiproton beam at the Brookhaven AGS, where the first measurements of the timelike structure in proton-antiproton annihilations to electron positron pairs were done. Subsequently, Barish worked at SLAC with Kendall, Taylor, Friedman and others in experiments that used the new two-mile electron linear accelerator to study deep inelastic scattering of electrons from nucleons. He studied form factors of the proton at high Q^2 at SLAC, comparing electrons with positrons.
Barish then started his own research program on the weak force. He did this by initiating neutrino physics (and the experimental program at large) at Fermilab, simply called NAL at that time. NAL experienced an interesting, significant and challenging transitional phase from early construction to operations; from building to research; from bricks and mortar to scientific investigation. Barish, together with Sciulli, developed the first neutrino experiment at Fermilab in 1970: Experiment 21. Barish and Sciulli were both young professors at Caltech and they worked with Maschke, head of NAL's Beam Transfer section, in what was one of the first experiments to be undertaken on the proton synchrotron at NAL. They were selected to investigate neutrino physics during the initial operation of the accelerator and continued until January 1973. The Caltech NAL researchers planned to carry their studies on neutrinos up to about 300 GeV. In July 1971, data existed only up to about 10 GeV. The Caltech NAL experiment, supported by the U.S. Atomic Energy Commission, hoped to produce and detect what we now know to be the W boson. These were all trailblazing research efforts and experiments built from the ground up. Barish's physics vision, hard work and dedication and his unparalleled talent in methodically and thoughtfully putting together a collaboration between engineers, scientists, technicians and construction people, is part of the foundation for what became a world-class science program with strong ties between universities and the National Laboratories of High Energy Physics research in the US.
Robert R. Wilson, NAL Director, told the NAL Users' Organization, at their annual meeting, that the first aim of experiments on the NAL accelerator system was the detection of a neutrino. "I feel that we then will be in business to do experiments on our accelerator, and I feel that this detection will come in the Caltech NAL experiment. The Caltech installation excites my envy; their enthusiasm and improvisation gives us a real incentive to provide them with the neutrinos they are waiting for." The program that Barish proposed designed and deployed at FNAL demonstrated the quark structure of the proton with neutrinos and produced the first observations of the Weak Neutral Current, helping establish the Glashow/Weinberg/Salam Standard Model.
After his work at Fermilab and after the discovery of the tau lepton at SLAC, Barish initiated the entire CLEO program on the physics of tau leptons (his CLEO research was funded by DOE). Barish realized that while CLEO was indeed a tau lepton factory there were very few results on tau physics coming out of it. Barish implemented a sophisticated physics program where the tau leptons were reconstructed and identified and well discriminated from other backgrounds. The program produced precision measurements of parameters for the tau lepton.
Circa 1984 Barish proposed an experiment with a primary goal of detecing heavy monopoles underground. MACRO, one of the founding and flagship experiments of the new underground laboratory at Gran Sasso. Barish served as co-spokesman for the MACRO detector at Gran Sasso. Barish's leadership established a standard for equal partnership in an international experiment. MACRO performed the most sensitive search to date for Grand Unified Monopoles and produced the most significant independent confirmation of atmospheric neutrino oscillations as discovered by the SuperKamiokande experiment.
Barish was the co-spokesman of the GEM collaboration for the SSC, which designed the detector system that would measure photons, electrons and muons precisely. The main physics goals of GEM were to perform the physics directed at signatures of the Higgs sector and new physics beyond the standard model. There is no doubt that the experience with developing the SSC detectors (an example that one can immediately map to the LHC detectors is the accordion calorimeter design and liquid argon EM calorimetry concept in Barish's GEM design) proved extremely valuable to the LHC effort that produced the discovery of the Higgs in 2012. Still today when we iterate on the design the LHC upgrades we use Barish's reports on the survey and evaluation of possible detector technologies.
Barish has led and advised non-accelerator and accelerator physics programs and experiments around the globe. His vision, wisdom, creativity, and persistence for building projects from the ground up are truly unparalleled by any one single researcher in history. Barish's science, technology, policy and leadership record is one of an exceptional researcher with very high standards on research, very talented on forming collaboration, extremely innovative and prolific in new ideas and groundbreaking techniques, and someone who is dedicated to materialize projects and designs meticulously and with realism. An outstanding example is his role in the extremely demanding position of Director of the Global Design Effort (GDE) for the International Linear Collider. This culminated in an outstanding shelf-ready end-to-end detailed design of a linear collider and its detectors with the full study of the cost and physics program. While the challenge of building such a machine rests with the complexities of forming international collaboration and the national investment of the host country and participating nations, the actual scientific results and conclusions of the Barish GDE report are already employed in multiple other facilities and machines in the US (e.g. LCLS at SLAC) and constitute a high-end product of DOE's vision and investment in future R&D for the furthering of fundamental science.
Barish's vision and wisdom has provided broad benefit to DOE and the entire U.S. particle physics planning effort. Barish served on HEPAP and chaired the Future Neutrino Physics subcommittee. Barish co-chaired the Long Range Plan for HEP with John Bagger, a study which set a standard that is evident in today's P5 plan. He has served on numerous review and advisory committees for experiments and universities. The high energy physics community speaks of Barish and his work with the uttermost respect be it at CERN, Gran Sasso, SNO Lab, or Japan. He still makes time to generously share his wisdom and vision on the field challenges and opportunities.
Barish's deep understanding of the work and discipline needed to move from R&D to production and delivery of complex physics projects is widely recognized as rescuing LIGO and setting it on the road to the historic discovery. There would be no LIGO (or the momentous gravitational wave discovery) without Barish, a statement made also by the other two Nobel laureates Kip Thorne also of Caltech, and Rai Weiss of MIT.
By Maria Spiropulu, Caltech HEP PI
Contact: Jing Zhang (jzhang312 AT hep.caltech.edu)
Future HEP experiments at the energy and intensity frontiers require fast and radiation hard inorganic scintillators to face the challenges of unprecedented events rate and harsh radiation environment . Supported by the DOE advanced detector R&D program, Dr. Ren-Yuan Zhu and his team have been working on this direction in the last several years in a close collaboration with industry, and have recently achieved remarkable progress in the development of novel ultra-fast yttrium doped BaF2 crystals and LuAG ceramic. Both materials, as well as LYSO crystals, are radiation hard for the HL-LHC environment. Optimized yttrium doping in BaF2 crystal suppresses its slow scintillation component of 600 ns decay time by a factor of 30, while maintaining the intensity of its fast scintillation component of sub-ns decay time unchanged. LuAG ceramics in a form of mm plates provides a cost-effective alternative for LYSO crystals for future HEP calorimeters.
This progress has been reported in the TIPP 2017 international conference at Beijing, China, the SCINT 2017 international conference at Chamonix, and the DPF CPAD 2017 conference at Albuquerque, NM this October. These interesting novel materials attract both academic and industrial research. Yttrium doped BaF2 crystal was assessed to be revolutionary in the CPAD conference. It is expected that it will find wide applications in future HEP experiments. Its small scintillation pulse width is ideal for the “Marie” project at Los Alamos a GHz hard X-ray imaging project.
The left photo below shows the team in the front of γ-ray and neutron irradiation sources on campus at Caltech. Team members Dr. Liyuan Zhang and Dr. Chen Hu are also shown in the right and middle photos below, working on a UV laser-based light monitoring system and photo-luminescence measurement system respectively. Additional information can be found in http://hep.caltech.edu/~zhu/.
By Dr. Ren-Yuan Zhu (zhu AT hep.caltech.edu), Caltech HEP ADR PI
Contact: Jing Zhang (jzhang312 AT hep.caltech.edu)
 At the HL-LHC, for example, 100 Mrad of ionization dose, 6×1014 p/cm2 of charged hadron fluence and 3×1015 n/cm2 of fast neutron fluence are expected.
Highly sensitive materials connect cosmic microwave background research with condensed-matter physics and quantum devices
Future projects aiming to measure the cosmic microwave background and other astronomical sources at mm/submm wavelengths, such as the CMB-S4 project, Inflation Probe mission, and Origins Space Telescope mission being studied right now, require large arrays of highly sensitive millimeter-wave and submillimeter (mm/submm) detectors. As with many areas of high-energy physics and astronomy, the detectors needed rely heavily on cutting-edge condensed-matter physics and materials science. We are engaged in an effort to systematically study, understand, and improve the properties of the dielectric materials that are used in many of these detectors. Silicon, in both amorphous and crystalline forms, promises to be an excellent dielectric for these uses because of its low loss and low noise, with characteristic loss (“loss tangent”) of 1 to 10 parts in 1 million! To date, neither form has been broadly used because of the effort required to learn how to reliably make devices with them and the lack of a systematic understanding of how the loss and noise are related to the way the devices are made.
Golwala's group at Caltech is aiming to solve this problem by carefully and systematically measuring the loss and noise properties of thin films two forms of silicon: hydrogenated amorphous silicon (a-Si:H) and crystalline silicon (c-Si). Recently, they presented results at the 17th International Workshop on Low Temperature Detectors in Kurume, Japan, showing that, indeed, these dielectrics, in thicknesses of 2 microns and 5 microns, provide intrinsic loss at GHz frequencies (10 cm wavelength) in the vicinity of 10 parts in 1 million and, when GHz power is applied, the loss can approach or go below 1 part in 1 million. They are now working to incorporate these materials into full detector devices and to test them at mm wavelengths (~100 times higher in frequency). These materials may also be useful in quantum computing devices using superconducting resonators or Josephson junctions.
This work is being undertaken by postdoctoral scholar Fabien Defrance, Research Assistant Professor Jack Sayers, JPL Senior Microdevices Engineer Andrew Beyer, and JPL Senior Research Scientist Peter Day.
This work is supported by NASA via the JPL Research and Technology Development (RTD) and the Astrophysics Research and Analysis (APRA) programs.
More information : golwala AT caltech.edu and http://pma.caltech.edu/content/sunil-golwala
By Sunil Golwala, Professor of Physics in the Division of Physics, Mathematics, and Astronomy at Caltech
Contact: Jing Zhang (jzhang312 AT hep.caltech.edu)
Device incorporating the thin crystalline silicon (cSi) dielectric into mm/submm detectors. The four large squares in the center are antennas that coherently collect incident light and output it to detectors. The transmission of the light in the antenna and to the detectors makes use of the cSi layer. The detectors themselves are arrayed around the edges of the antenna. Each one of them is a kinetic inductance detector, combining a titanium nitride inductor (sensitive to incoming light) with a niobum parallel-plate capacitor (the large rectangles). The capacitors also make use of the cSi layer, as in the test devices in the first picture.