# Department of Physics

Professor Calvin W. Johnson

Web pages

The Eightfold group as of October 2018: Changfeng, Ryan, Raul, Sasha, Jordan, Oliver, Ken, Stephanie.

Fall 2021 member: Ryan, Sasha, Jordan, Oliver, Stephanie, Kris, Mandy, Austin, Dustin,  Heng, and Vladimir

Important for students! All communication for classes by e-mail will be by your SDSUid

The BIGSTICK shell-model code

"Seven things about...." from SDSU News Center

Science fiction and the human condition

### News

August 19, 2021: Several new publications:

“Lipkin model on a quantum computer,” M. J. Cervia, A. B. Balantekin, S. N. Coppersmith, C. W. Johnson, P.J. Love, C. Poole, K. Robbins, M. Saffman, Phys. Rev. C 104. 024305 (201)

“The nucleon-pair approximation for nuclei from spherical to deformed regions,” G.F. Fu and C. W. Johnson, Phys. Rev. C 104 024312 (2021) Editor’s Suggestion”

“Benchmarking angular-momentum projected Hartree-Fock as an approximation,” S. M. Lauber, H. C. Frye, and C. W. Johnson, J. Phys. G. 48, 095107 (2021).

June 24, 2021: Published B. Dai, B.S. Hu. Y.Z. Ma, J. G. Li, S. M. Wang, C. W. Johnson, and F. R. Xu, : “Tensor force role in b-decays analyzed within the Gogny-interaction shell model,” Phys. Rev. C 103, 064327 (2021).

May 19, 2021: Published: R. Zbikowski, C. W. Johnson, et al, "Rotational bands beyond the Elliott model," J. Phys. G 48, 075102 (2021).

May 16, 2021: I have been elected to the board of the FRIB-Theory Alliance

Apr 8, 2021:  Congratulations to Hayden Frye of our research group, named as the 2021 outstanding graduating physics student!

Apr 8, 2021:  A preprint Stephanie Lauber (Ph.D student), Hayden Frye (physics major), and C. W. Johnson, "Benchmarking projected Hartree-Fock as an approximation," arXiv:2104.03455.

Feb 15, 2021: Published: "Nucleon-pair coupling scheme in Elliott's SU(3) model," G.J. Fu, C. W. Johnson, P. van Isacker, and Z.Z. Ren, Phys. Rev. C, 103, L021302 (2021)

Feb 8, 2020: A preprint from Ph.D student Oliver Gorton and J. Escher, "Cross sections for neutron-induced reactions from surrogate data," arXiv:2102.03452

Jan 27, 2021:, A preprint, "Nucleon-pair coupling scheme in Elliott's SU(3) model," G.J. Fu, C. W. Johnson, P. van Isacker, and Z.Z. Ren, arXiv:2101.11774

Dec 17, 2020: A preprint: G. J. Fu and C. W. Johnson, "The nucleon-pair approximation for nuclei from spherical to deformed reigions," arXiv: 2012.09560

Nov 24, 2020: Oliver Gorton, a Ph.D student in my group, is on a new paper just published "Measurements of proton capture in the A=100110 mass region", PRC 102, 055806 (2020), Olivas-Gomez et al.

Nov 18, 2020: A preprint (accepted for publication by J. Phys. G): R. Zbikowski, C. W. Johnson, et al, "Rotational bands beyond the Elliott model," arXiv:2011.08307

Nov 16, 2020: Another paper published, C. W. Johnson et al,  J. Phys. G: Nucl. Part. Phys. 47 123001 (2020). White paper from a workshop I ran two years ago.

October 5, 2020: Jordan Fox, Ph.D student, gets a SCGSR fellowship! This will allow him to carry out research at Lawrence Livermore National Lab.

September 18, 2020: A paper published, Exact sum rules with approximate ground states, C. W. Johnson. K. A. Luu, and Y. Lu, J. Phys G. 47 105107 (2020)

August 24, 2020: A paper published, From deformed Hartree-Fock to the nucleon-pair approximation, G.-J. Fu and C. W. Johnson, Phys. Lett. B 809, 135705 (2020)

May 11, 2020: A paper published, Uncertainty quantification of an empirical shell-model interaction using principal component analysis, Jordan Fox, C. W. Johnson, and R. Navarro Perez,  PRC 101, 054308 (2020), also available at arXiv:1911.05208.

April 29, 2020: A paper published, Unmixing symmetries, C. W. Johnson, PRL 124, 172502 (2020), also available at arXiv:1911.09142

April 2, 2020:  I was named an outstanding review for Journal of Physics G: Nuclear Physics, for 2019.

Dec 3,2019:  A paper published: "No-core shell model calculations of the photonuclear cross section of 10B", M. K. G. Kruse, W.E. Ormand, and CWJ, EPJA 55, 225 (2019), and another paper posted: "From bound states to the continuum," arXiv:1912.00451

Nov 22, 2019: Two recent papers posted:

“Uncertainty quantification of an empirical shell-model interaction using principal component analysis,” Jordan M. R. Fox and C.W. Johnson, arXiv:1911.05208
“Unmixing symmetries,” C. W. Johnson, arXiv:1911.09142

Sept 26, 2019: Paper published (with modified title): "The union of rotational and vibrational modes..." with C.F. Jiao,   Phys. Rev. C 100, 031303(R) (2019).

Sept 19, 2019: New paper on the arXiv:  "From deformed Hartree-Fock to the nucleon pair approximation,"  (with G. J. Fu) arXiv: 1909.08785

Aug 12, 2019: Two papers on the arXiv:

(with C. F. Jiao)  arXiv:1908.01873. UPDATE 9/18/2019 accepted Phys Rev C.

and

“Entanglement and collective neutrino oscillations,” M. J. Cervia, A. V. Patwardhan, A. B. Balantekin, S. N. Coppersmith, and CWJ, arXiv:1908.03511. UPDATE 9/19/2019 accepted Phys Rev. D. 100, 083001(2019)

Jul 12, 2019: Published article for non-experts: Shadows of Symmetries, Nuclear Physics News International 29, 18-21 (2019)(behind a paywall, I'm afraid to say)

Nov 20, 2018: Published paper: Convergence and efficiency of angular momentum projection ...     J. Phys. G 46, 015101 (2019).

Sept 20, 2018: A new e-print conference proceeding on large-basis diagonalization of the shell model.

Aug 20, 2018: A new e-print with Dr. Changfeng Jiao on the arXiv: “Convergence and efficiency of angular momentum projection for many-body systems”

July 1, 2018: I organized a two-week workshop on Connecting Bound States to the Continuum, for FRIB at MSU

June 1, 2018: Gave a short talk on the shell model at CIPANC 2018.

Apr 9, 2018:  I have been appointed an associate editor at Physical Review C

Mar 29,2018: A paper, Transition sum rules in the shell model, has been published and is now online!

Mar 2, 2018: I have been named an outstanding referee by the American Physical Society.

Feb 27, 2018: My talk at TRIUMF on strength function sum rules is online.

Jan 25, 2018BIGSTICK, an interacting shell-model code, has finally been publically released as free, open-source code!

The manual is available on the arXiv

Dec 1, 2017: A paper, Projection of angular momentum by linear algebra, co-written with former SDSU physics major Kevin O'Mara, published and now online!

Oct 9, 2017: A new paper on the arXiv, "Transition sum rules in the shell model."

Sept 14, 2017: My story, "Of the Beast in the Belly," has been anthologized in an audiobook collection, "Year's Top Hard Science Fiction Stories."

Sept 13, 2017: A new paper on the arXiv, "Projection of angular momentum by linear algebra," co-written with former SDSU physics major Kevin O'Mara: Update: accepted for publication in Phys. Rev. C!

Sept 12, 2017: Congratulations to Raul Herrera, (UCSD physics grad student but part of my group) who has been awarded a U.S. Department of Energy (DOE) Office of Science Graduate Student Research (SCGSR) grant to spend 4 months at Lawrence Berkeley National Lab working on his thesis research, focusing on Gamow-Teller transitions above A = 65. These are highly competitive grants, and winning one is a tremendous achievement!

Aug 9, 2017:  I have a chapter in a book coming out, also available on the arXiv: "The anatomy of atomic nuclei."  In addition, a new preprint is posted on the arXiv: "Tracing the evolution of nuclear forces under the similarity renormalization group"

March 5, 2017: My talk "Ab initio rotational bands in medium and heavy nuclei" from the TRIUMF workshop on "Progress on Ab Initio Techniques in Nuclear Physics"  on is now available online.

Feb 22, 2017: Congratulations to Jordan Fox for winning a Parallel Computing Summer Research Internship at Los Alamos National Lab!

Feb 3, 2017: The paper on backbending has been published and is selected as an Editor's suggestion!

July 5, 2016:  An e-print, "Quasi-dynamical symmetries in backbending the chromium isotopes," by Raul Herrera and C. W. Johnson has been posted on the arXiv.

May, 2016: I have been awarded 30 MILLION core-hours for computation via ALCC (ASCR Leadership Computing Challenge)

Aug 31, 2015:  "Systematics of strength function sum rules," : Phys. Lett. B 750, 72 (2015).

March 11, 2015: "Spin-orbit decomposition of ab initio nuclear wavefunctions" : Phys. Rev. C 91, 034313 (2015)

November 5, 2014: I have a science fiction story appearing in the December issue of ANALOG SCIENCE FICTION AND FACT.  You can read a sample of it here.

August 18, 2014: I have started a blog, for posting essays on science, science fiction, and related topics.

August 7, 2014: Micah Schuster (Ph.D student) wins award for best     summer student research poster at Lawrence Livermore National Lab. He also won the past two years.

### Recent publications

"Projection of angular momentum by linear algebra," C. W. Johnson and K. D. O'Mara, Phys. Rev. C 96, 064304 (2017)

"Quasidynamical symmetries in the chromium isotopes," R. Herrera and C. W. Johnson,  Phys. Rev. C 95, 024303 (2017).

"Systematics of strength function sum rules,": Phys. Lett. B 750, 72 (2015).

"Spin-orbit decomposition of ab initio nuclear wavefunctions" C. W. Johnson  Phys. Rev. C 91, 034313 (2015)

"Isoscalar and isovector pairing in a formalism of quartets," M. Sambataro, N. Sandulescu, and C. W. Johnson, Phys. Lett B 740, 137 (2015).

"Testing the spin-cutoff parameterization with shell-model calculations," W. M. Spinella and C. W. Johnson, Phys. Rev. C 90, 014315 (2014), see also arXiv:1304.7746

"Operator evolution for ab initio theory of light nuclei" M. D. Schuster,  S. Quaglioni, C. W. Johnson, E. D. Jurgenson, and P. Navratil, Phys. Rev. C 90,  011301(R) (2014), see also arXiv:1402:7106

"Factorization in large-scale many-body calculations," C. W. Johnson, W. E. Ormand, and P. G. Krastev, Comp. Phys. Comm. 184, 2761-2774 (2013), see also arXiv:1303:0905    This paper describes the algorithms underlying the BIGSTICK shell-model code, at the heart of much of our research.

### Other recent writing

"The Age of Discovery" (fiction, To Shape the Dark)

"Of the Beast in the Belly" (fiction at Asimov's SF magazine)