--- title: "The Rutgers/Maryland 12-inch corpus · Cyclotron Info" canonical: https://cyclotroninfo.com/library/rutgers-umd/ description: "A reading guide to the Rutgers/Maryland 12-inch cyclotron papers — the best-documented amateur-origin machine — linked to the authors' own hosted copies with Internet Archive fallbacks." generated: 2026-11-12 note: "Markdown rendering of the canonical HTML page, generated at build for AI assistants and text tools. Figures and interactive elements are described, not reproduced. On Design Guide rules the source quote, this site's paraphrase and this site's editorial note are labelled separately and must not be conflated." licence: "Datasets CC BY 4.0, census snapshot CC BY-NC 4.0 (https://cyclotroninfo.com/data/); cite as Cyclotron Info, cyclotroninfo.com" --- # The Rutgers/Maryland 12-inch corpus The Rutgers 12-inch cyclotron — begun in a New Jersey basement in 1995 by two undergraduates, a Rutgers teaching accelerator from 2001, and since 2016 the centerpiece of a University of Maryland capstone program — is the best-documented amateur-origin cyclotron in this site's census. Its builders wrote the machine up continuously for two decades: subsystem memos during construction, conference papers once it matured, and neutron-physics reports after the move to Maryland. This page is a reading guide to that record: 17 documents, in the order the machine earned them. Every link below points at the authors' own hosted copies, on the [NPL 12-Inch Cyclotron Papers page](http://www.nuclearphysicslab.com/npl/npl-home/accelerators/cyclotrons/12-inch-cyclotron-papers/). That collection is the canonical home of these documents, and they are its authors' copyright, so this site links rather than hosts. Where the Internet Archive holds a verified snapshot, an “archived” badge follows the link, so the record outlives any one server. For the machine itself, see the census entries for the [9-inch prototype](https://cyclotroninfo.com/builds/#rutgers-9), the [12-inch](https://cyclotroninfo.com/builds/#rutgers-12), and the [Maryland 19-inch successor](https://cyclotroninfo.com/builds/#umd-19-2016), the [program history](https://cyclotroninfo.com/builds/#prog-koeth), and the builders' sites: [koethcyclotron.org](http://koethcyclotron.org/) (subsystem documentation), [the project history at timkoeth.com](http://timkoeth.com/uncategorized/tims-cyclotron/), and the [*Cyclotrons!* video series](https://cyclotroninfo.com/library/resources/#video-lectures). Why this corpus matters to a builder: it is the one sustained record of a small machine written *while being figured out*, at amateur scale, in memo form — the measurements, the models that did and did not match them, and the high-voltage problems reported as problems. 16 of the documents have been mined into the [Design Guide](https://cyclotroninfo.com/design-guide/) (267 rules cite them, each with a page-referenced verbatim quote), and the German COLUMBUS school cyclotron's builders write that their ion source “was built after the pattern of Tim Koeth”, citing Part I of the ion-source studies ([dg-1524](https://cyclotroninfo.com/design-guide/?domain=ion-source,project-management&q=Koeth#dg-1524)). It is the clearest documented case of this record teaching a machine into existence elsewhere. ## Build and commissioning memos (2005–2015) - [The 9-Inch Cyclotron construction writeup (with drawings)](http://www.nuclearphysicslab.com/npl/wp-content/uploads/nine_inch_cyclotron_with_dwg.pdf) [archived Sep 2026](https://web.archive.org/web/20260928031333/http://www.nuclearphysicslab.com/npl/wp-content/uploads/nine_inch_cyclotron_with_dwg.pdf) Timothy W. Koeth · undated scan; the machine ran 1995–1999 · [library entry](https://cyclotroninfo.com/library/#lib-284) · 35[Design Guide](https://cyclotroninfo.com/design-guide/) rules An 18-page scanned writeup of the original 9-inch-magnet prototype, drawings included — the same chamber later run between 12-inch poles. One of the most reproducible small-cyclotron documents on the open web. - [Report on the 12-Inch Cyclotron Magnet Study: Measurements, Modeling, and Future Plans](http://www.nuclearphysicslab.com/npl/wp-content/uploads/12_inch_magnet_studies_4.pdf) [archived Sep 2026](https://web.archive.org/web/20260928031327/http://www.nuclearphysicslab.com/npl/wp-content/uploads/12_inch_magnet_studies_4.pdf) Timothy W. Koeth · c. 2005 (PDF dated June 2005) · [library entry](https://cyclotroninfo.com/library/#lib-275) · 19[Design Guide](https://cyclotroninfo.com/design-guide/) rules Field measurements and modeling of the 12-inch magnet, with the plans that shaped the pole-tip work that followed. - [Theoretical Calculations and Measurements of the Dee Voltage in the Rutgers 12-Inch Cyclotron](http://www.nuclearphysicslab.com/npl/wp-content/uploads/12_inch_dee_voltage.pdf) [archived Nov 2024](https://web.archive.org/web/20241104043833/http://www.nuclearphysicslab.com/npl/wp-content/uploads/12_inch_dee_voltage.pdf) Timothy W. Koeth · September 2005 · [library entry](https://cyclotroninfo.com/library/#lib-018) · 11[Design Guide](https://cyclotroninfo.com/design-guide/) rules Dee capacitance estimated by summing parallel-plate sections, then dee voltage measured three independent ways. The memo behind this site's dee-voltage design rules. - [Rutgers 12-Inch Cyclotron Ion Source Studies: Part I](http://www.nuclearphysicslab.com/npl/wp-content/uploads/ion_source_studies_part_1.pdf) [archived Sep 2026](https://web.archive.org/web/20260928031301/http://www.nuclearphysicslab.com/npl/wp-content/uploads/ion_source_studies_part_1.pdf) Timothy W. Koeth · 2006 · [library entry](https://cyclotroninfo.com/library/#lib-013) · 6[Design Guide](https://cyclotroninfo.com/design-guide/) rules The filament ion source and first central-orbit studies — the source pattern the German COLUMBUS school cyclotron later adopted by name. - [Observation of Betatron Motion in the Rutgers 12-Inch Cyclotron](http://www.nuclearphysicslab.com/npl/wp-content/uploads/Betatron_Studies.pdf) [archived Sep 2026](https://web.archive.org/web/20260928031330/http://www.nuclearphysicslab.com/npl/wp-content/uploads/Betatron_Studies.pdf) Timothy W. Koeth, Stuart C. Hanebuth, William Schneider, Daniel Hoffman · April 2006 · [library entry](https://cyclotroninfo.com/library/#lib-276) · 17[Design Guide](https://cyclotroninfo.com/design-guide/) rules First observed betatron motion in the machine, found consistent with radially increasing proton energy. - [Rutgers 12-Inch Cyclotron Ion Source Studies: Part II (Ion Source Simulations and Measurements)](http://www.nuclearphysicslab.com/npl/wp-content/uploads/IonSourceStudiesII_Jan_27_2008.pdf) [archived Sep 2026](https://web.archive.org/web/20260928031325/http://www.nuclearphysicslab.com/npl/wp-content/uploads/IonSourceStudiesII_Jan_27_2008.pdf) Timothy W. Koeth, Stuart C. Hanebuth, Daniel E. Hoffman, William S. Schneider · December 2007 (file revised January 2008) · [library entry](https://cyclotroninfo.com/library/#lib-272) · 20[Design Guide](https://cyclotroninfo.com/design-guide/) rules SIMION 3-D particle tracking brought to bear on the ion source, with the measurements that checked it. - [Rutgers 12-Inch Cyclotron Electrostatic Deflector](http://www.nuclearphysicslab.com/npl/wp-content/uploads/Deflector_Dec_31_2011.pdf) [archived Sep 2026](https://web.archive.org/web/20260928031326/http://www.nuclearphysicslab.com/npl/wp-content/uploads/Deflector_Dec_31_2011.pdf) Timothy W. Koeth, Timothy S. Ponter, Daniel E. Hoffman, William S. Schneider, James E. Krutzler · September 2010 (file revised December 2011) · [library entry](https://cyclotroninfo.com/library/#lib-273) · [related library entry](https://cyclotroninfo.com/library/#lib-025) · 22[Design Guide](https://cyclotroninfo.com/design-guide/) rules The electrostatic deflection channel built to verify final beam energy directly — including the high-voltage problems along the way. Companion to the 2010 conference slides in the library. - [Comparison of Azimuthally Varying with Constant Gradient Magnetic Fields with the Rutgers 12-Inch Cyclotron](http://www.nuclearphysicslab.com/npl/wp-content/uploads/AVF_study_Dec_31_2011.pdf) [archived Sep 2026](https://web.archive.org/web/20260928031326/http://www.nuclearphysicslab.com/npl/wp-content/uploads/AVF_study_Dec_31_2011.pdf) Timothy W. Koeth, George A. Hine, Daniel E. Hoffman, James E. Krutzler, Timothy S. Ponter, Aaron J. Rosenberg, Kiersten J. Ruisard, William S. Schneider · June 2011 (file revised December 2011) · [library entry](https://cyclotroninfo.com/library/#lib-274) · 29[Design Guide](https://cyclotroninfo.com/design-guide/) rules Weak-focusing versus azimuthally-varying-field pole tips compared on one machine — the interchangeable-pole-tip experiment that few laboratories of any size can run. - [Field Mapping in Cyclotron Magnets](http://www.nuclearphysicslab.com/npl/wp-content/uploads/Mag_Field_Mapping_July_6_2015.pdf) [archived Sep 2026](https://web.archive.org/web/20260928031301/http://www.nuclearphysicslab.com/npl/wp-content/uploads/Mag_Field_Mapping_July_6_2015.pdf) Timothy W. Koeth, James E. Krutzler · July 2015 · [library entry](https://cyclotroninfo.com/library/#lib-006) · 8[Design Guide](https://cyclotroninfo.com/design-guide/) rules 2-D field mapping of four interchangeable pole-tip sets, written explicitly so others can set up the same measurement. ## Conference papers (2013–2016) - [The Rutgers Cyclotron: Placing Student's Careers on Target](http://www.nuclearphysicslab.com/npl/wp-content/uploads/we1pb02.pdf) [archived Nov 2024](https://web.archive.org/web/20241104053911/http://www.nuclearphysicslab.com/npl/wp-content/uploads/we1pb02.pdf) K. Ruisard, G. Hine, T. Koeth, A. Rosenberg · 2013 · Cyclotrons 2013, WE1PB02 · [library entry](https://cyclotroninfo.com/library/#lib-280) · 17[Design Guide](https://cyclotroninfo.com/design-guide/) rules The program's outcomes paper, written by its students: what building and running the machine did for the careers of the people who did it. - [A Novel Optical Method for Measuring Beam Phase and Width in the Rutgers 12-Inch Cyclotron](http://www.nuclearphysicslab.com/npl/wp-content/uploads/we1pb04.pdf) [archived Nov 2024](https://web.archive.org/web/20241104053025/http://www.nuclearphysicslab.com/npl/wp-content/uploads/we1pb04.pdf) J. Gonski, S. Burcher, S. Lazarov, J. Krutzler, T. Koeth, B. Beaudoin · 2013 · Cyclotrons 2013, WE1PB04 · [library entry](https://cyclotroninfo.com/library/#lib-281) · 13[Design Guide](https://cyclotroninfo.com/design-guide/) rules Beam phase and width measured optically — bunch structure resolved within a single RF cycle on a 12-inch machine. - [Rutgers 12-Inch Cyclotron: Dedicated to Training Through Research and Development](http://www.nuclearphysicslab.com/npl/wp-content/uploads/weppt024.pdf) [archived Jul 2026](https://web.archive.org/web/20260713131158/http://www.nuclearphysicslab.com/npl/wp-content/uploads/weppt024.pdf) T. W. Koeth, A. J. Rosenberg, J. E. Krutzler, T. S. Ponter, W. S. Schneider, D. E. Hoffman · 2013 · Cyclotrons 2013, WEPPT024 · [library entry](https://cyclotroninfo.com/library/#lib-282) · 17[Design Guide](https://cyclotroninfo.com/design-guide/) rules The machine-overview paper the census entry cites: history, subsystems, and the training-through-R&D model. - [Beam Physics Demonstrations with the Rutgers 12-Inch Cyclotron](http://www.nuclearphysicslab.com/npl/wp-content/uploads/weppt025.pdf) [archived Nov 2024](https://web.archive.org/web/20241104043011/http://www.nuclearphysicslab.com/npl/wp-content/uploads/weppt025.pdf) T. W. Koeth · 2013 · Cyclotrons 2013, WEPPT025 · [library entry](https://cyclotroninfo.com/library/#lib-283) · 15[Design Guide](https://cyclotroninfo.com/design-guide/) rules The beam-physics teaching repertoire: focusing, betatron motion, resonances, and diagnostics as classroom demonstrations. - [Undergraduate Education with the Rutgers 12-Inch Cyclotron](http://www.nuclearphysicslab.com/npl/wp-content/uploads/CAARI_Koeth_Cyclotron_2.pdf) [archived Aug 2026](https://web.archive.org/web/20260823040347/http://www.nuclearphysicslab.com/npl/wp-content/uploads/CAARI_Koeth_Cyclotron_2.pdf) Timothy W. Koeth · 2014 · CAARI 2014 (published in Physics Procedia, 2015) · [library entry](https://cyclotroninfo.com/library/#lib-038) The education-program paper, also available by DOI via its library entry. - [Betatron Tune Characterization of the Rutgers 12-Inch Cyclotron for Different Magnetic Poles Configurations](http://www.nuclearphysicslab.com/npl/wp-content/uploads/rutgers_betatron_ch1.pdf) [archived Sep 2026](https://web.archive.org/web/20260928031330/http://www.nuclearphysicslab.com/npl/wp-content/uploads/rutgers_betatron_ch1.pdf) C. Hernalsteens, T. S. Ponter, B. Beaudoin, T. W. Koeth, K. Ruisard, M. Miller · 2016 · PDF dated 2016; described as a USPAS 2015 course product by the NPL collection page · [library entry](https://cyclotroninfo.com/library/#lib-277) · 10[Design Guide](https://cyclotroninfo.com/design-guide/) rules Tunes measured from betatron motion across pole configurations — written when the machine anchored the two-week USPAS cyclotron course. ## The neutron program (2017–2020) - [Neutron Production with a 12-Inch Cyclotron](http://www.nuclearphysicslab.com/npl/wp-content/uploads/Neutrons_Nov_18_2017_ver1_reduced.pdf) [archived Sep 2026](https://web.archive.org/web/20260928031331/http://www.nuclearphysicslab.com/npl/wp-content/uploads/Neutrons_Nov_18_2017_ver1_reduced.pdf) Timothy W. Koeth · updated November 2017 · [library entry](https://cyclotroninfo.com/library/#lib-278) · 18[Design Guide](https://cyclotroninfo.com/design-guide/) rules D–D fusion neutrons from a deuterium-loaded titanium target: RF halved for deuterons, the radiological controls that made it permissible, and the calibration against a NIST-traceable ²⁵²Cf source. - [Measurement of Neutron Diffusion Time from Fast Pulsed Systems](http://www.nuclearphysicslab.com/npl/wp-content/uploads/Neutron_Diff_March_7_2020.pdf) [archived Sep 2026](https://web.archive.org/web/20260928031331/http://www.nuclearphysicslab.com/npl/wp-content/uploads/Neutron_Diff_March_7_2020.pdf) Timothy W. Koeth, Luke Gilde, Scott Moroch · updated March 2020; marked DRAFT by its authors · [library entry](https://cyclotroninfo.com/library/#lib-279) · 10[Design Guide](https://cyclotroninfo.com/design-guide/) rules The cyclotron pulsed down to a 10 µs beam-on-target window to time neutron diffusion in a polyethylene moderator — the fundamental-physics measurement the census entry describes. ## How this page is preserved The documents stay where their authors put them; this site records each link's Internet Archive snapshot and shows it beside the live link once verified, following the same [preservation practice](https://cyclotroninfo.com/about/methodology/) as the census and library citations. If a link above has gone dark and shows no archived badge yet, the snapshot usually exists — check the URL directly at web.archive.org, and report the dead link so the page can be updated. > **Page provenance.** Last reviewed: 5 September 2026 · [NPL 12-Inch Cyclotron Papers (titles and dates transcribed from each PDF)](http://www.nuclearphysicslab.com/npl/npl-home/accelerators/cyclotrons/12-inch-cyclotron-papers/) · [Methodology](https://cyclotroninfo.com/about/methodology/) · [Report a correction](mailto:info@cyclotroninfo.com?subject=Correction%3A%20The%20Rutgers%2FMaryland%2012-inch%20corpus) · [Changelog](https://cyclotroninfo.com/changelog/)