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News from the Nuclear Science Division at Berkeley Lab
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Nuclear Science Division Newsletter
In this issue:July, 2016

STAR Ultra-peripheral collisions precisely probe di-pion masses

Art McDonaldFigure 1 The mass distribution of 384,000 photoproduced π+π- pairs with pT < 100 MeV, fit to a mixture of ρ, ω and direct ππ.
Art McDonaldFigure 2 Target density distribution, determined by a Fourier-Bessel transform. The points are for ρ0 accompanied by mutual Coulomb excitation (MCE, black) and MCE with a single neutron in each direction (red). The blue shows the systematic uncertainties.

The STAR collaboration has released a new analysis of di-pion photoproduction in ultra-peripheral collisions (UPCs), with 384,000 events, 100 times better statistics than previous measurements. The improved statistics allow for several new measurements: an observation of ρ−ω interference in the π+π- final state (only the 2nd time this has been seen), observation of photoproduction of a high mass π+π- state, observation of two diffraction minima in dσ/dt, and, from that, a measurement of the density profile of the gold nucleus. Spencer Klein presented these results at Deep Inelastic Scattering 2016, in Hamburg, in April.

Figure 1 (left) shows the di-pion mass spectrum (black points with error bars), together with a fit to a modified Soding formula, with interfering amplitudes for ρ -> π+π- (blue curve), ω-> π+π- (red curve) and direct π+π-photoproduction (dotted black line). The dotted blue line shows interference between the ρ and direct π+π-, while the dotted red line shows the interference between the ρ and the ω. The ω causes a visible kink in the spectrum around 782 MeV, the ω mass. The χ2/DOF is 314/297, showing that this this mixture does a good job of describing the data. A further analysis found a fourth state, with a mass of 1653 ± 10 MeV; this appears consistent with the ρ3(1690).

The density profile of the target is extracted from the cross-section for coherent photoproduction; the coherent component is found by fitting and subtracting the incoherent. Two diffraction minima are clearly visible in the coherent ρ0 pT spectrum. A Fourier-Bessel transform is applied to the spectrum to find the two-dimensional density distribution, shown in Fig. 2. The uncertainty at low impact parameters (b) is likely due to windowing, and the negative contribution at large |b| is due to interference from the 2nd nucleus, but, in between, the edges of the target are well determined. The distribution has a FWHM of 6.17 ± 0.12 fm (stat. only). This is precise enough for an eventual comparison with the density distribution of a gold nucleus. Nuclear shadowing might suppress production in the center of the nucleus; the distribution is also sensitive to the presence of a neutron skin. Similar studies are envisioned for a future electron-ion collider.

Reference:
S. Klein for the STAR Collaboration, arXiv:1606.02754

Radiation Mapping Truck is tested in Singapore

Truck The diverse suite of systems and sensors on board the LBNL and UC Berkeley developed Radiological Multisensor Analysis Platform, RadMAP.

In January 2016, Applied Nuclear Physics (ANP) Program scientists traveled to Singapore for a joint technology trial of their Radiological Multisensor Analysis Platform (RadMAP) test bed for mobile radiation detection. The RadMAP truck (right), is designed to evaluate multi-sensor fusion techniques in mobile radiation detection. The RadMAP system combines large area gamma-ray detection and imaging systems with an integrated suite of contextual sensors including video and LIDAR. The system can provide real time detection, localization, and identification of radioactive material while moving and can fuse the radiation data with data from the contextual sensors to provide a 3D reconstruction of the environment.

The trial scenarios included passive monitoring at maritime and land border ports of entry to demonstrate the use of RadMAP in screening passenger vehicles and cargo containers, as well as controlled measurements using radiological sources to quantitatively assess RadMAP’s detection and imaging performance. In an urban search scenario, the RadMAP system was used to detect, identify, and image several gamma-ray test sources within a complex, built up environment.

The test was a joint effort of the US Department of Homeland Security’s (DHS) Domestic Nuclear Detection Office (DNDO) and Singapore’s Ministry of Home Affairs (MHA). The system was deployed in Singapore for a period of three weeks and was supported by ANP’s Ren Cooper, Mark Bandstra, and Joey Curtis along with officials from DNDO and MHA. During the technology trial, a range of measurements were made in order to assess how RadMAP-like technology could be used to augment more conventional radiation detection capabilities in Singapore.

The trial concluded with a visitor’s day, during which the RadMAP system was presented to representatives of the Singapore government, including MHA’s chief scientist, and its capabilities demonstrated in a directed search scenario. In the image below left, Ren Cooper and Mark Bandstra are pictured in the RadMAP truck, demonstrating the technology to Singapore officials.

Truck LBNL’s Ren Cooper, far left bottom, and Mark Bandstra, far right, provide an overview of RadMAP’s diverse array of systems.
Truck The LBNL team set-up a mobile operations staging center outside the truck at each site to enable collaborators to observe the real-time measurements and data products generated by the truck.

Further information on the RadMAP system and the work of the Applied Nuclear Physics Program can be found on the ANP website at http://anp.lbl.gov/.

Lattice QCD for nuclear physics

Cal

Computation now plays an essential role in every area of nuclear physics research. Lattice QCD (LQCD) is a cornerstone of computational nuclear theory providing the connection between one-to-few nucleon systems with the fundamental theory of nuclear physics (NP), QCD. The application of LQCD to low-energy NP relevant to current and future experiments, e.g. the search for neutrinoless double beta-decay, is an exascale challenge. LBNL is home to the newest LQCD group focussed on NP applications, a part of the CalLat Collaboration, supported in part by the DOE under SciDAC 3. CalLat was founded by Wick Haxton (PI), Pavlos Vranas (coPI: LLNL) and others including André Walker-Loud (recently returned to LBNL). We are also lucky to have Thorsten Kurth who moved from NSD to NERSC, as well as CRD staff Esmond Ng, Abhinav Sarje, Sam Williams and Chao Yang, and a number of postdocs and grad students at LBNL, LLNL and UC Berkeley.

Cal

Tremendous effort has gone into developing performant routines and libraries for basic LQCD software. In contrast, there has been a comparatively negligible amount of effort invested in developing tools needed for LQCD applications to NP. In our first application, we developed improved two-nucleon operators that allowed for the first time, the calculation of elastic two-nucleon (NN) scattering phase shifts beyond the simplest S-wave interactions [1].
For next generation NP applications highlighted in the recent Nuclear Science Long Range Plan, it is critical to develop more sophisticated and efficient LQCD software focussed on two and more nucleons. We aim to develop such a domain-specific-framework (DSF) featuring a performance portable backend designed by computer scientists plugged into exascale development with a novel high-level interface (Python) decoupling the physics description from the computational details. The figure to the right shows an envisioned software stack with the new DSF pieces highlighted in red/blue. Members of CalLat also contribute to the development of QUDA and QPHIX, specialized libraries for NVIDIA GPUs and new Intel CPUs respectively. This DSF will provide the foundation of LQCD software for next-generation NP applications in the exascale era.

Reference:

[1] E. Berkowitz, T. Kurth, A. Nicholson, B. Joo, E. Rinaldi, M. Strother, P. Vranas and A. Walker-Loud, for the CalLat Collaboration, Two-Nucleon Higher Partial-Wave Scattering from Lattice QCD, arXiv:1508.00886.

Fragments

 
Scouts Learn about Nuclear Science. On April 23, the Nuclear Science Division (NSD), in collaboration with the Advanced Light Source and Workforce Development and Education department, hosted over 200 girl scouts, boy scouts and their adult leaders at the 6th annual Nuclear Science Day for Girl Scouts and Boy Scouts event at Berkeley Lab. This year’s theme was neutrinos, in celebration of the recent Nobel Prize in Physics. This event patch, which was given to each participant, featured the Sudbury Neutrino Observatory (SNO) detector.
 
In the morning the scouts first attended a short lecture on the “ABC” (alpha, beta and gamma) of nuclear science delivered by our division director Barbara Jacak, followed by a short presentation on neutrinos and the SNO experiment. Following the lectures, the participants were divided into different groups and rotated between activity stations throughout the day. These activities include building the atomic model with marshmallows, constructing a simple electroscope, learning how to use a Geiger counter and the ALARA principle, as well as attending a career forum where panelists with backgrounds in nuclear science talked about their career. The participants also toured the Advanced Light Source to learn about accelerators and their operation.
 

The boy scouts who completed all the activities and a pre-event worksheet met all the requirements of the nuclear science merit badge. At this year’s event, girl scouts received the “Get to know Nuclear” patch, sponsored by the American Nuclear Society, after completing the same requirements as the boy scouts.

A photo-journal and tweets of the event can be found at https://als.exposure.co/science-scouts and https://twitter.com/NucSciDayLBNL, respectively.
 

 

On April 14-15, 2016, the Institute for Resilient Communities (IRC) co-hosted the Second International Symposium for Resilient Communities in Koriyama City, Japan, along with the Koriyama City Hall (KYC) and Fukushima Renewable Energy Institute, AIST (FREA).

Topics pertaining to radiation resilience, including energy, health, seismic, radiological, and health, as well as education, outreach, and community resilience were covered by over 20 speakers.

As part of the Second Symposium, the IRC and KYC jointly organized a Next Generation Fukushima Workshop for participating university students from Japan, Berkeley, and South Korea. Selected students, scientists, and speakers also had the unique opportunity to tour inside the Fukushima Dai-ichi Nuclear Power Plant.

The photo shows the Koriyama City Mayor and city staff, Rockefeller Foundation Chief Resilience Officers, and participating students from UC Berkeley, Japan, and South Korea, as well as Berkeley Lab personnel.

 

NSD veteran Al Smith turns 90 The NSD held a belated celebration of Alan “Al” Smith’s 90th birthday on June 8. Al began his career at Berkeley Lab in 1953 working on radiation monitoring at the Bevatron. Over the intervening decades, he moved into studies of environmental radiation. Since his retirement in mid-1990s, he has been contributing to the low-background counting efforts at the Berkeley Low Background Facility. He has assayed a large number samples for epochal neutrino experiments, including the Sudbury Neutrino Observatory (SNO), KamLAND, and Daya Bay experiments, and has continued to do so for the current and future generation of underground experiments such as CUORE, LZ and Majorana. At this surprise party, his colleagues presented to him a “germanium trophy” as a birthday present. This trophy consists of a bare germanium crystal sitting atop a jar of rock samples from several underground labs and assay samples from experiments. A special cake, decorated with the primordial uranium and thorium chains, was made for this occasion. Al gingerly cut and enjoyed the corner of the cake where there were not any radioactive isotopes.

 

Berkeley hosts SORMA. Researchers from the Applied Nuclear Physics group organized and presented their work at the quadrennial Symposium on Radiation Measurements and Applications (SORMA) West was held at the UC Clark Kerr Campus last week, at which over 400 attendees gathered to discuss the latest research on radiation detection for homeland and national nuclear security. Representatives from the DOE, DHS, and DOD were invited to summarize the challenges, advances, and lessons learned from investments and demonstrations over the last decade. Paper topics ranged from passive detection for wide-area search to active interrogation of shielded special nuclear materials. Advances in gamma and neutron detection and imaging technologies were also presented by authors and over 20 industrial exhibitors. The photos shows SORMA 16 general chair John Valentine introducing the conference.

 

NSD Director Barbara Jacak has been elected to the American Academy of Arts and Sciences. The academy includes national and international scholars, writers and artists, as well as businessmen and political and philanthropic leaders.

 

 

NSDs Jackie Gates has been awarded a DOE Early Career Award. The award will allow her to initiate a new program of experiments aimed at determining the masses and atomic numbers of super heavy elements, and then to delve further into understanding the nuclear properties of these superheavy nuclei by obtaining detailed information on their nuclear structure. More specifically, it will use be used to commission the new heavy element mass separator, FIONA and to perform the first detailed studies of superheavy element masses and spectroscopy.

 

 

Grazyna Odyniec has won the Wybitny Polak competition for science. This award, from the Polskiego Godla Promocyjnego foundationis given to a Polish expatriate scientist on the West Coast. The award was presented in Los Angeles, by the Polish consul general there.

 

Newsletter Notes
Please send any comments, including story suggestions to Spencer Klein at srklein@lbl.gov.
 
Previous issues of the newsletter are available at:
https://commons.lbl.gov/display/nsd/NSD+Newsletter.
Copyright © 2016 Berkeley Lab, All rights reserved.


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