Accelerator Physics

The lunar nightapproximately 354 hours of complete solar darkness with surface temperatures reaching-173 °Cwas formally ranked as the single highest-priority unsolved technology challenge in civil space exploration by NASA's Space Technology Mission Directorate in 2024. This paper proposes and rigorously evaluates the Orbital Solar Relay Network (OSRN): a constellation of CubeSat-class spacecraft in 100 km polar low lunar orbit equipped with deployable photovoltaic arrays and diode-pumped solid-state lasers (DPSSL, λ = 1064 nm) that transmit harvested solar energy to photovoltaic laser power converter (PVLPC) arrays on the lunar surface throughout the lunar night. Corrected beam optics analysisusing the Gaussian beam propagation modelconfirms that laser WPT is uniquely suited to the LLO-to-surface geometry. A 10 cm transmitter aperture at 1064 nm produces a beam waist of 67.7 cm at 100 km range and 135.5 cm at 200 km, yielding

Planetary defense is increasingly recognized as a matter of long-term strategic resilience, yet the legal and financial mechanisms necessary to support sustained preparedness remain largely undeveloped. While significant attention has been devoted to asteroid detection, characterization, and mitigation technologies, comparatively little analysis has focused on the capital architectures required to finance planetary defense capabilities at scale. The absence of dedicated funding frameworks creates a structural gap between scientific objectives, governmental mandates, and the resources necessary to maintain enduring readiness. This paper examines how existing legal authorities, public finance models, and emerging capital market instruments may be adapted to support planetary defense infrastructure across the detection, monitoring, mitigation, and response continuum. Drawing upon developments in infrastructure finance, sovereign risk management, insurance-linked securities, strategic reserve policy, and international space governance, the paper explores mechanisms capable of mobilizing both public and private capital while preserving accountability, transparency, and international cooperation. Particular attention is given to resilience-linked financing structures, public-private investment vehicles, and treaty-compatible frameworks designed to align long-term economic incentives with planetary security objectives.

The CMS detector is designed around a large 4 T superconducting solenoid, enclosed in a 12 000-tonne steel return yoke. A detailed map of the magnetic field is required for the accurate simulation and reconstruction of physics events in the CMS detector, not only in the inner tracking region inside the solenoid but also in the large and complex structure of the steel yoke, which is instrumented with muon chambers. Using a large sample of cosmic muon events collected by CMS in 2008, the field in the steel of the barrel yoke has been determined with a precision of 3 to 8% depending on the location.

At the LNF of INFN an IR array detector with a ns response time has been built and assembled in order to collect the IR image of the e⁻/e⁺ sources at DAΦNE. Such detector is made by 32 bilinear pixels with a pixel size of 50x50 μm² and a response time of 1 ns. The device with its electronic board has been assembled for the installation on the e⁺ ring of DAΦNE in the framework of an experiment funded by the INFN Vth Committee dedicated to beam diagnostics. A preliminary characterization of few pixels of the array and of the electronics has been carried out at the IR beamline SINBAD at DAΦNE. In particular the detection of the IR source of the e⁻ beam has been observed using four pixels of the array acquiring signals simultaneously with a 4 channels scope at 1GHz and at 4 Gsamples/s. The acquisition of 4 pixels allowed monitoring in real time differences in the bunch signals in the vertical direction. Preliminary analysis of data is presented and discussed. In particular we will outli...

We present the electromagnetic design study of a multi cell,  g = 0.9, 650 MHz elliptic superconducting radiofrequency cavity, which can be used for accelerating H -particles in the linear accelerator part of a Spallation Neutron source. The design has been optimized for maximum achievable acceleration gradient by varying the geometry parameters of the cavity, for which a simple and general procedure is evolved that we describe in the paper. For the optimized geometry, we have studied the higher order modes supported by the cavity, and the threshold current for the excitation of the regenerative beam break up instability due to dipole modes has been estimated. Lorentz force detuning studies have also been performed for the optimized design and the calculations are presented to find the optimum location of the stiffener ring to compensate for the Lorentz force detuning.

As a consequence of the new radiation source for ultrashort VUV pulses at DELTA, which is based on the interaction of electrons with fs laser pulses, coherent THz radiation is emitted. Simulations of the laser-electron interaction, particle dynamics and radiation spectrum, as well as the optical and mechanical design of a dedicated THz beamline are presented. First experimental results including laser-electron overlap diagnostics and characterization of the THz radiation are discussed.

The TRIUMF Advanced Rare Isotope Laboratory (ARIEL) is funded since 2010 June by federal and BC Provincial governments. In collaboration with the University of Victoria, TRIUMF is proceeding with construction of a new target building, connecting tunnel, rehabilitation of an existing vault to contain the electron linear accelerator, and a cryogenic compressor building. TRIUMF starts construction of a 300 keV thermionic gun, and 10 MeV Injector cryomodule (EINJ) in 2012; the designs being complete. The 25 MeV Accelerator Cryomodule (EACA) follows in autumn 2013. TRIUMF is embarking on major equipment purchases and has signed contracts for 4K cryogenic plant and four subatmospheric pumps, a 290 kW c.w. klystron and highvoltage power supply, 80 quadrupole magnets, EINJ tank and lid, and four 1.3 GHz niobium 9-cell cavities from a local Canadian supplier. The low energy beam transport and beam diagnotics are being installed at the ISAC-II/VECC test facility. Procurement is anticipated October 2012 for the liquid He distribution system. The ARIEL project is described in Refs. . The conventional infrastructure consists of four contracts: the main ARIEL construction, demolition and excavation, and the Stores and Badge buildings replacements. The latter are necessitated by site congestion. The new Compressor Building (CB), for gaseous helium management, forms part of the ARIEL package. In addition there are major renovations that will transform the former Proton Hall to the Electron Hall (e-hall). Chernoff-Thompson Architects led a successful bid for the overall architecture and engineering contract, awarded October 2010. The Stores and Badge building construction is complete and occupancy was taken Sept 2011 and Dec 2011, respectively. The demolition and excavation work started October 2011, and completed April 2012. The ARIEL main construction package was awarded Feb 2012. There is substantial completion of the tunnel and B2 level of the actinide target preparation labs, target hall and Rare Isotope Beams annexe. The annexe will contain mass separators and front-end accelerators. The CB is well advanced: roofing and envelope cladding, mechanical and electrical rough-in, are all proceeding on-track for occupancy in December 2012.

The feasibility of a CLIC-LHC based FEL-nucleus collider is investigated. It is shown that the proposed scheme satisfies all requirements of an ideal photon source for the Nuclear Resonance Fluorescence method. The physics potential of the proposed collider is illustrated for a beam of Pb nuclei.

This paper presents a quantitative radiological analysis of the Artemis II Orion spacecraft hull, examining the aluminum-lithium (Al-Li 2195) pressure vessel's capacity to attenuate gamma radiation in the deep space environment beyond Earth's magnetosphere. Using linear attenuation coefficients derived from the National Institute of Standards and Technology (NIST) XCOM photon cross-section database, Beer-Lambert attenuation law, Compton scattering kinematics, and

At the LNF of INFN an IR array detector with a ns response time has been built and assembled in order to collect the IR image of the e⁻/e⁺ sources at DAΦNE. Such detector is made by 32 bilinear pixels with a pixel size of 50x50 μm² and a response time of 1 ns. The device with its electronic board has been assembled for the installation on the e⁺ ring of DAΦNE in the framework of an experiment funded by the INFN Vth Committee dedicated to beam diagnostics. A preliminary characterization of few pixels of the array and of the electronics has been carried out at the IR beamline SINBAD at DAΦNE. In particular the detection of the IR source of the e⁻ beam has been observed using four pixels of the array acquiring signals simultaneously with a 4 channels scope at 1GHz and at 4 Gsamples/s. The acquisition of 4 pixels allowed monitoring in real time differences in the bunch signals in the vertical direction. Preliminary analysis of data is presented and discussed. In particular we will outli...

DAFNE operation restarted in September 2003, after a six month shut-down for the installation of FINUDA, a magnetic detector dedicated to the study of hypernuclear physics. FINUDA is the third experiment running on DAFNE and operates while keeping on place the other detector KLOE. During the shut-down both Interaction Regions have been equipped with remotely controlled quadrupoles in order to operate at different solenoid fields. Among many other hardware upgrades one of the most significant is the reshaping of the wiggler pole profile to improve the field quality and the machine dynamic aperture. Commissioning of the collider in the new configuration has been completed in short time. The peak luminosity delivered to FINUDA has reached 6 10^31 s-1cm-2, with a daily integrated value close to 4 pb-1.

The CMS detector is designed around a large 4 T superconducting solenoid, enclosed in a 12 000-tonne steel return yoke. A detailed map of the magnetic field is required for the accurate simulation and reconstruction of physics events in the CMS detector, not only in the inner tracking region inside the solenoid but also in the large and complex structure of the steel yoke, which is instrumented with muon chambers. Using a large sample of cosmic muon events collected by CMS in 2008, the field in the steel of the barrel yoke has been determined with a precision of 3 to 8% depending on the location.

DETAILED ABSTRACT

THE PROTON ACCELERATOR PACK: A Technical White Paper on the Engineering, Physics, and Safety Protocols for a Miniaturized Cyclotron-Based Particle Beam System

Author: Anthony Jordan Blair
Date: March 2026
Status: Engineering Specification — PHCA/BPA Applications Series

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The miniaturization of particle acceleration technology for portable applications represents a convergence of cyclotron physics, radiation safety engineering, and advanced materials science that has been technically feasible for decades yet deliberately unexplored due to institutional gatekeeping and safety concerns. Drawing from established accelerator design principles dating to Ernest Lawrence's 11-centimeter cyclotron (1930), compact medical proton therapy research achieving 8-centimeter cyclotron diameters, and recent advances in laser-plasma acceleration and dielectric wall accelerator (DWA) technology, this paper presents the first comprehensive engineering framework for a backpack-mounted proton accelerator system—designated the Proton Accelerator Pack (PAP-1) .

The PAP-1 operates on the principle of a fixed-field alternating gradient (FFAG) synchrotron scaled to wearable dimensions, utilizing a non-scaling lattice with FDF triplet sequences for beam stability across the energy range of 5-15 MeV. The complete system architecture comprises six integrated subsystems: (1) a hydrogen gas duoplasmatron ion source producing protons via electrical discharge, (2) a miniature cyclotron/synchrotron hybrid employing superconducting niobium-titanium (NbTi) magnets generating 4-6 Tesla fields within an 8-centimeter form factor, (3) a dielectric wall accelerator (DWA) booster section imposing a linear time gradient of 48.6 MeV/m/ns for precision bunch formation prior to main acceleration, (4) active beam focusing and collimation optics utilizing quadrupole triplets and dispersion-compensated bend sections, (5) a particle thrower assembly with magnetic confinement capable of delivering 10 ns - 1 μs pulses at 1-100 Hz repetition rates with spot sizes adjustable from 2-10 mm, and (6) an integrated safety interlock system with redundant radiation monitoring, beam permit authorization, and fail-safe internal beam dump.

The device achieves peak pulse power of 70 MW from compact klystron units operating at 2.008 MHz with 3-microsecond pulse duration, while maintaining average power consumption of 2-5 kW through high-density lithium-ion polymer battery arrays with pulse-forming network capacitors. Thermal management is accomplished via pulse-tube cryocoolers maintaining superconducting magnet temperatures below 20 K, supplemented by liquid cooling loops and radiative panels. Radiation shielding follows IAEA Technical Reports Series No. 283 and IPEM Report 75 guidelines, incorporating layered borated polyethylene (5 cm) for thermal neutron capture, lead (2 cm) for gamma attenuation, and optional depleted uranium (1 cm) for high-energy neutron moderation, achieving total system mass of approximately 32 kg and volume of 29 L—within wearable limits.

The critical engineering challenge addressed is stream crossing inhibition. When two independently accelerated proton beams intersect, catastrophic failure modes become possible including vacuum polarization (localized spacetime metric distortion), beam-beam instability leading to uncontrolled divergence, coherent pair production generating matter-antimatter pairs, and resonant cavity formation creating energy feedback to accelerators. The PAP-1 incorporates orthogonal beam path design, frequency diversity (each unit operating at unique RF frequency), active phase cancellation monitoring, and GPS-interlocked geofencing preventing units from approaching within 500 meters. Given the existential risk associated with uncontrolled stream convergence, this specification mandates that only one operational unit shall ever be constructed.

The paper further analyzes the system through the Proclean Hierarchical Constraint Architecture examining physical (PHCA) and Blair Persistence Architecture (BPA) frameworks, component integration (L1), documentary evidence including complete engineering schematics (L2), institutional regulatory compliance with IAEA and CFR standards (L3), narrative management of the technology's cultural representation (L4), and covert operational risks including unauthorized unit construction (L5). A comprehensive safety protocol includes two-handed arming, real-time beam parameter monitoring, and emergency abort systems that terminate beam to internal dump within 1 microsecond of power loss.

This document serves three purposes: (1) to establish that portable proton accelerator technology is technically feasible using existing component technologies, (2) to provide sufficient technical detail for informed engineering oversight and regulatory review, and (3) to codify the ethical principle that some knowledge, once gained, must be voluntarily limited. The crossing streams hazard is not a plot device but a genuine physical risk demanding absolute operational constraint. The Fifth Day for particle physics is not the day the first portable accelerator is built—it is the day the scientific community demonstrates the wisdom to build only one.

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Keywords: proton accelerator, cyclotron, FFAG synchrotron, dielectric wall accelerator, particle beam, radiation safety, stream crossing, vacuum polarization, PHCA, BPA

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"What persists, prospers. What fragments, fails. The knowledge to build this has persisted for ninety years. Now we must have the wisdom to limit its instantiation."

Calculating spontaneous radiation emission from long undulator sections such as those present in the European XFEL is important for several diagnostics and science cases. For realistic setups, and including effects of electron beam focusing, emittance and energy spread in the electron beam, these calculations should be performed numerically. We present these calculations for several electron beam and undulator parameters performed by various codes.

BESSY is proposing a new facility to demonstrate the cascading of two high-gain harmonic-generation stages for the generation of FEL radiation. This facility, called STARS, is planned for lasing in the wavelength range 40 nm to 70 nm. A 325-MeV CW driver linac provides a peak current of 500 A at a bunch charge of 1 nC. The linac consists of a normal-conducting gun, three superconducting TESLA-type modules modified for CW operation, a thirdharmonic unit to linearize the RF potential and a singlestage bunch compressor. This paper discusses the facility layout and the main operating parameters.

Highly anisotropic, beam-like neutron emission with peak flux of the order of 10 9 n/sr was obtained from light nuclei reactions in a pitcher-catcher scenario, by employing MeV ions driven by a subpetawatt laser. The spatial profile of the neutron beam, fully captured for the first time by employing a CR39 nuclear track detector, shows a FWHM divergence angle of ~ 70 , with a peak flux nearly an order of magnitude higher than the isotropic component elsewhere. The observed beamed flux of neutrons is highly favourable for a wide range of applications, and indeed for further transport and moderation to thermal energies. A systematic study employing various combinations of pitchercatcher materials indicates the dominant reactions being d(p, n+p) 1 H and d(d,n) 3 He. Albeit insufficient cross-section data are available for modelling, the observed anisotropy in the neutrons' spatial and spectral profiles is most likely related to the directionality and high energy of the projectile ions.

We would like to thank the directors of the institutions who have hosted ILC meetings: KEK, ANL/FNAL/SLAC/U. Colorado (Snowmass), INFN/Frascati, IIT/Bangalore, TRI-UMF/U. British Columbia, U. Valencia, IHEP/Beijing and DESY. We are grateful for the support of the Funding Agencies for Large Colliders (FALC), chaired by R. Petronzio of INFN, and we thank all of the international, regional and national funding agencies whose generous support has made the ILC Reference Design possible. Each of the GDE regional teams in the Americas, Asia and Europe are grateful for the support of their local scientific societies, industrial forums, advisory committees and reviewers.

We consider three scenarios for the recirculating electron linear accelerator (RLA) of a linac-ring type electronproton collider based on the LHC (LHeC): i) a pulsed linac with a final beam energy of 60 GeV ["p-60"], ii) a higher luminosity configuration with two cw linacs and energyrecovery (ERL) also at 60 GeV ["erl"], and iii) a high energy option using a pulsed linac with 140-GeV final energy ["p-140"]. We discuss parameters, synchrotron radiation, footprints, and performance for the three scenarios.

The high luminosity requirements and the option of a polarized positron beam present a great challenge for the positron source of a future linear collider. This paper provides a comprehensive overview of the latest proposed design for the baseline positron source of the International Linear Collider (ILC). We report on recent progress and results concerning the main components of the source: including the undulator, capture optics, and target.

Sub-atomic physics at the energy frontier probes the structure of the fundamental quanta of the Universe. The Large Hadron Collider (LHC) at CERN opens for the first time the "terascale" (TeV energy scale) to experimental scrutiny, exposing the physics of the Universe at the subattometric (~10 -19 m, 10 -10 as) scale. The LHC will also take the science of nuclear matter to hitherto unparalleled energy densities (low-x physics). The hadron beams, protons or ions, in the LHC underpin this horizon, and also offer new experimental possibilities at this energy scale. A Large Hadron electron Collider * , LHeC, in which an electron (positron) beam of energy (70 to 140 GeV) is in collision with one of the LHC hadron beams, makes possible terascale lepton-hadron physics. The LHeC is presently being evaluated in the form of two options, "ring-ring" and "linac-ring", either of which operate simultaneously with pp or ion-ion collisions in other LHC interaction regions. Each option takes advantage of recent advances in radio-frequency, in linear acceleration, and in other associated technologies, to achieve ep luminosity as large as 10 33 cm -2 s -1 . An overview is presented here of the scientific motivation and technical status of the LHeC project. *

The China ADS (C-ADS) driver linac is composed of two parallel 10 MeV injectors and a main linac which boosts the beam further to 1.5 GeV. There are two design schemes for the injectors based on different working frequency and superconducting cavity structures and both are under developing at the same time on IHEP and IMP, respectively. The Injector Scheme I, which is proposed by IHEP, works at 325 MHz, the same frequency of the main linac, and superconducting Spoke cavities with geometry beta of 0.12, the same type of cavity as the main linac too, are applied after the RFQ. In this paper, the latest progress on physics design will be presented.

It is widely accepted that the Accelerator Driven System (ADS) is one of the most promising technical approach to solve the problem of the nuclear wastes, a potential threaten to the sustainable development of the nuclear fission energy. An ADS study program was approved by Chinese Academy of Sciences at 2011, which aims to design and built an ADS demonstration facility with the capacity of more than 1000 MW thermal power within the following 20 years. The 15 MW driver accelerator will be designed and constructed by the Institute of High Energy Physics (IHEP) and Institute of Modern Physics (IMP) of China Academy of Sciences. This linac is characterized by the 1.5 GeV energy, 10mA current and CW operation. It is composed by two parallel 10 MeV injectors and a main linac integrated with fault tolerance design. The superconducting acceleration structures are employed except the RFQ. In this paper the general considerations and the beam dynamics design of the driver accelerator will be presented.

The construction of the ILC tangential to Tevatron ring will give opportunity to investigate electron-proton, positron-proton, electron-antiproton, positron-antiproton interactions at 1 TeV center of mass energy. The analysis of the lepton-hadron collisions in these energy region is very important both for understanding of strong interaction dynamics and for adequate interpretation of future LHC and VLHC data. In addition, ILC-Tevatron collider will provide a possibility to realize photon-hadron collisions in the same energy region using Compton backscattered laser photon off ILC electron beam. Main parameters of these colliders are estimated and their physics search potential is briefly discussed.

Different limitations on luminosity of linac-ring type colliders coming from beam dynamics issues are considered for the examples of the ep options of the THERA and Linac⊗LHC proposals. It is shown that L = 1.3 × 10 31 for THERA and L = 2.7 × 10 32 for Linac⊗LHC can be achieved for round beams case. Corresponding sets of parameters are given with the explanations.

We report on the experimental observation of beam-like neutron emission with peak flux of the order of 10 9 n/sr, from light nuclei reactions in a pitcher-catcher scenario, by employing MeV ions driven by high power laser. The spatial profile of the neutron beam, fully captured for the first time by employing a CR39 nuclear track detector, shows a FWHM divergence angle of ∼ 70 • , with a peak flux nearly an order of magnitude higher than the isotropic component elsewhere. The observed beamed flux of neutrons is highly favourable for a wide range of applications, and indeed for further transport and moderation to thermal energies. A systematic study employing various combinations of pitcher-catcher materials indicates the dominant reactions being d(p, n+p) 1 H and d(d,n) 3 He. Albeit insufficient cross-section data are available for modelling, the observed anisotropy in the neutrons' spatial and spectral profiles are most likely related to the directionality and high energy of the projectile ions.