N. Mokhov

The MANX muon cooling demonstration experiment

MANX is an experiment to prove that effective six- dimensional (6D) muon beam cooling can be achieved in a Helical Cooling Channel (HCC) using ionization- cooling with helical and solenoidal magnets in a novel configuration. The aim is to demonstrate that 6D muon beam cooling is understood well enough to plan intense neutrino factories and high-luminosity muon colliders. The experiment consists of the HCC magnet that envelops a liquid helium energy absorber, upstream and downstream instrumentation to measure the beam parameters before and after cooling, and emittance matching sections between the detectors and the HCC.

Modeling and design of the ilc test area beam absorbers at fermilab

Detailed MARS 15 simulations have been performed on energy deposition and shielding of the proposed ILC Test Area absorbers. It is designed for up to 50 kW of 800- MeV electron beam power and provides unlimited occupancy conditions in the experimental hall. ANSYS analysis based on the calculated energy deposition maps confirms robustness of the proposed design of the absorbers and beam windows for normal operation and for various failure modes.

Energy deposition studies for the High-Luminosity Large Hadron Collider inner triplet magnets

A detailed model of the high-luminosity LHC inner triplet region with new large-aperture Nb3Sn magnets, field maps, corrector packages, and segmented tungsten inner absorbers was built and implemented into the fluka and mars15 codes. Detailed simulations have been performed coherently with the codes on the impact of particle debris from the 14-TeV center-of-mass pp-collisions on the short- and long-term stability of the inner triplet magnets. After optimizing the absorber configuration, the peak power density averaged over the magnet inner cable width is found to be safely below the quench limit at the luminosity of 5×1034u2009u2009cm−2u2009s−1. For the anticipated lifetime integrated luminosity of 3000u2009u2009fb−1, the peak dose calculated for the innermost magnet insulator ranges from 20 to 35xa0MGy, a figure close to the commonly accepted limit. Dynamic heat loads to the triplet magnet cold mass are calculated to evaluate the cryogenic capability. fluka and mars results on energy deposition are in very good agreement.

A Muon beam for cooling experiments

Within the framework of the Fermilab Muon Collider Task Force, the possibility of developing a dedicated muon test beam for cooling experiments has been investigated. Cooling experiments can be performed in a very low intensity muon beam by tracking single particles through the cooling device. With sufficient muon intensity and large enough cooling decrement, a cooling demonstration experiment may also be performed without resolving single particle trajectories, but rather by measuring the average size and position of the beam. This allows simpler, and thus cheaper, detectors and readout electronics to be used. This paper discusses muon production using 400MeV protons from the Linac, decay channel and beamline design, as well as the instrumentation required for such an experiment, in particular as applied to testing the Helical Cooling Channel (HCC) proposed by Muons Inc.

Energy deposition studies of block-coil quadrupoles for the LHC luminosity upgrade

At the LHC upgrade luminosity of 1035 cm-2 s-1, collision product power in excess of a kW is deposited in the inner triplet quadrupoles. The quadrupole field sweeps secondary particles from pp-collisions into the superconducting (SC) coils, concentrating the power deposition at the magnetic mid-planes. The local peak power density can substantially exceed the conductor quench limits and reduce component lifetime. Under these conditions, block-coil geometries may result in overall improved performance by removing the superconductor from the magnetic mid-planes and/or allowing increased shielding at such locations. First realistic energy deposition simulations are performed for an interaction region based on block-coil quadrupoles with parameters suitable for the LHC upgrade. Results are presented on distributions of power density and accumulated dose in the inner triplet components as well as on dynamic heat loads on the cryogenic system. Optimization studies are performed on configuration and parameters of the beam pipe, cold bore and cooling channels. The feasibility of the proposed design is discussed.

Radiation levels around the Fermilab Main Injector extraction septa

The Fermilab Main Injector extraction system will be capable of delivering a uniform 120 GeV beam of /spl sim/3/spl times/10/sup 13/ protons per spill to the fixed target experiments (with spill time of 1 sec). Up to 2% of the beam is expected to be lost at the extraction septum and the Lambertson magnet. As a result, one expects increased radiation levels around the septa compared to other parts of the Main Injector. Realistic Monte-Carlo simulations have been performed to estimate the instantaneous and residual radiation levels in the beam extraction region. The results of these studies are presented and implications are discussed.

Enhancement of heat removal using concave liquid metal targets for high-power accelerators

The need is increasing for development of high-power targets and beam dump areas for the production of intense beams of secondary particles. The severe constraints arising from a megawatt beam deposited on targets and absorbers call for nontrivial procedures to dilute the beam. This study describes the development of targets and absorbers and the advantages of using flowing liquid metal in concave channels first proposed by IFMIF to raise the liquid metal boiling point by increasing the pressure in liquid supported by a centrifugal force. Such flow with a back-wall is subject to Taylor-Couette instability. The instability can play a positive role of increasing the heat transfer from the hottest region in the target/absorber to the back-wall cooled by water. Results of theoretical analysis and numerical modeling of both targets and dump areas for the IFMIF, ILC, and RIA facilities are presented.

Suppression of muon backgrounds generated in the ILC beam delivery system

Muon background suppression at the ILC collider detectors was studied by MARS 15 Monte Carlo simulation with a detailed description of the ILC BDS beam line and tunnel of 1.6-km length. Muon suppressions of about 1/5 and 1/50 were obtained for the donut- and wall-shape muon-spoilers, respectively.

Simulation Aspects of Beam Collimation and Their Remedies in the MARS14 Code

Simulation aspects of beam collimation are described along with a number of tools and methods developed and used within the MARS14 framework. The tools and methods were implemented in order to relieve the burden of simulations needed for reliable calculations required for design of efficient collimation systems at high-intensity accelerators and colliders.

Collider and detector protection at beam accidents

Dealing with beam loss due to abort kicker prefire is considered for hadron colliders. The prefires occured at Tevatron (Fermilab) during Run I and Run II are analyzed and a protection system implemented is described. The effect of accidental beam loss in the Large Hadron Collider (LHC) at CERN on machine and detector components is studied via realistic Monte Carlo calculations. The simulations show that beam loss at an unsynchronized beam abort would result in severe heating of conventional and superconducting magnets and possible damage to the collider detector elements. A proposed set of collimators would reduce energy deposition effects to acceptable levels. Special attention is paid to reducing peak temperature rise within the septum magnet and minimizing quench region length downstream of the LHC beam abort straight section.