The ISOLDE facility Catherall, R; Andreazza, W; Breitenfeldt, M ...
Journal of physics. G, Nuclear and particle physics,
09/2017, Letnik:
44, Številka:
9
Journal Article
Recenzirano
Odprti dostop
The ISOLDE facility has undergone numerous changes over the last 17 years driven by both the physics and technical community with a common goal to improve on beam variety, beam quality and safety. ...Improvements have been made in civil engineering and operational equipment while continuing developments aim to ensure operations following a potential increase in primary beam intensity and energy. This paper outlines the principal technical changes incurred at ISOLDE by building on a similar publication of the facility upgrades by Kugler (2000 Hyperfine Interact. 129 23-42). It also provides an insight into future perspectives through a brief summary issues addressed in the HIE-ISOLDE design study Catherall et al (2013 Nucl. Instrum. Methods Phys. Res. B 317 204-207).
CERN has launched a study phase to evaluate the feasibility of a new high-intensity beam dump facility at the CERN Super Proton Synchrotron accelerator with the primary goal of exploring Hidden ...Sector models and searching for Light Dark Matter, but which also offers opportunities for other fixed target flavour physics programs such as rare tau lepton decays and tau neutrino studies. The new facility will require—among other infrastructure—a target complex in which a dense target/dump will be installed, capable of absorbing the entire energy of the beam extracted from the SPS accelerator. In theory, the target/dump could produce very weakly interacting particles, to be investigated by a suite of particle detectors to be located downstream of the target complex. As part of the study, a development design of the target complex has been produced, taking into account the handling and remote handling operations needed through the lifetime of the facility. Two different handling concepts have been studied and both resulting designs are presented.
PUMA, antiProton unstable matter annihilation Aumann, T.; Bartmann, W.; Boine-Frankenheim, O. ...
The European physical journal. A, Hadrons and nuclei,
05/2022, Letnik:
58, Številka:
5
Journal Article
Recenzirano
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PUMA, antiProton Unstable Matter Annihilation, is a nuclear-physics experiment at CERN aiming at probing the surface properties of stable and rare isotopes by use of low-energy antiprotons. ...Low-energy antiprotons offer a very unique sensitivity to the neutron and proton densities at the annihilation site, i.e. in the tail of the nuclear density. Today, no facility provides a collider of low-energy radioactive ions and low-energy antiprotons: while not being a collider experiment, PUMA aims at transporting one billion antiprotons from ELENA, the Extra-Low-ENergy Antiproton ring, to ISOLDE, the rare-isotope beam facility of CERN. PUMA will enable the capture of low-energy antiprotons by short-lived nuclei and the measurement of the emitted radiations. In this way, PUMA will give access to the so-far largely unexplored isospin composition of the nuclear-radial-density tail of radioactive nuclei. The motivations, concept and current status of the PUMA experiment are presented.
Abstract
CERN’s North Area comprises several target and experimental systems and is a zone of interest for future development. Provision of beam to this area relies upon several beam-intercepting ...devices located in various branched transfer lines from the Super Proton Synchrotron. In several lines, these include a primary production target system of beryllium plates followed by a combined collimation, attenuation and dump device made from a set of aluminum, copper and iron blocks and known as a ‘TAX’ (Target Attenuator for eXperimental areas). These may operate in a range of configurations depending on experimental needs. Future operational regimes with higher beam intensities (increased from a current specification of 1.5× 10
13
to 4.0× 10
13
p
+
/pulse), shorter pulse times (4.8 s reduced to 1.2 s), greater repetition rates (14.4 s cycle time reduced to 7.2 s) and ten times the annual intensity place more stringent thermo-structural demands on these existing devices, beyond their original specification. This contribution outlines the engineering analysis, including beam-matter interaction studies and thermo-structural simulations, carried out to assess their robustness under such conditions.
A new parasitic, mixed-field, neutron-dominated irradiation station has been recently commissioned at the European Laboratory for Particle Physics (CERN). The station is installed within the neutron ...time-of-flight (n_TOF) facility, taking advantage of the secondary radiation produced by the neutron spallation target, with neutrons ranging from 0.025 eV to several hundreds of MeV. The new station allows radiation damage studies to be performed in irradiation conditions that are closer to the ones encountered during the operation of particle accelerators; the irradiation tests carried out in the station will be complementary to the standard tests on materials, usually performed with gamma sources. Samples will be exposed to neutron-dominated doses in the MGy range per year, with minimal impact on the n_TOF facility operation. The station has 24 irradiation positions, each hosting up to100cm3of sample material. In view of its proximity to the n_TOF target, inside protective shielding, the irradiation station and its operating procedures have been carefully developed taking into account the safety of personnel and to avoid any unwanted impact on the operation of the n_TOF facility and experiments. Due to the residual radioactivity of the whole area around the n_TOF target and of the irradiated samples, access to the irradiation station is forbidden to human operators even when the n_TOF facility is not in operation. Robots are used for the remote installation and retrieval of the samples, and other optimizations of the handling procedures were developed in compliance with radiation protection regulations and the aim of minimizing doses to personnel. The sample containers were designed to be radiation tolerant, compatible with remote handling, and subject to detailed risk analysis and testing during their development. The whole life cycle of the irradiated materials, including their post-irradiation examinations and final disposal, was considered and optimized.
The beam dump facility (BDF) is a project for a new facility at CERN dedicated to high intensity beam dump and fixed target experiments. Currently in its design phase, the first aim of the facility ...is to search for light dark matter and hidden sector models with the Search for Hidden Particles (SHiP) experiment. At the core of the facility sits a dense target/dump, whose function is to absorb safely the400GeV/cSuper Proton Synchrotron (SPS) beam and to maximize the production of charm and beauty mesons. An average power of 300 kW will be deposited on the target, which will be subjected to unprecedented conditions in terms of temperature, structural loads and irradiation. In order to provide a representative validation of the target design, a prototype target has been designed, manufactured, and tested under the SPS fixed-target proton beam during 2018, up to an average beam power of 50 kW, corresponding to 350 kJ per pulse. The present contribution details the target prototype design and experimental setup, as well as a first evaluation of the measurements performed during beam irradiation. The analysis of the collected data suggests that a representative reproduction of the operational conditions of the beam dump facility target was achieved during the prototype tests, which will be complemented by a postirradiation examination campaign during 2020.
A relatively new area of research suggests that naturally occurring mentoring relationships may influence the development of adolescents by protecting against risk behaviors. Few studies have ...explored how these relationships function to reduce risk behavior among youth, especially in the school context. Based on previous research and theory, we proposed and tested a mediation model, which hypothesized that school attachment mediated the longitudinal association between school-based natural mentoring relationships and risk behaviors, including eight indicators of substance use and violence. Students (N = 3320) from 65 high schools across eight states completed a self-report questionnaire at baseline and 1-year follow-up. The sample was comprised of youth with an average age of 14.8 years and an almost equal percentage of females (53%) and males from various ethnic backgrounds. Tests for mediation were conducted in Mplus using path analysis with full information maximum likelihood procedures and models adjusted for demographic covariates and baseline level of the dependent variable. Results suggested that natural mentoring relationships had a protective indirect influence on all eight risk behaviors through its positive association on the school attachment mediator. Implications are discussed for strengthening the association between school-based natural mentoring and school attachment to prevent risk behaviors among youth.
The 2010 edition of the Highway Capacity Manual (HCM 2010) provides new capacity models for single-lane and multilane roundabouts, which generally predict lower capacity than other popular models ...previously used in the United States. Acknowledging that both roundabout design practices and the public's use of roundabouts are still maturing in the United States, the HCM recommends local calibration of the capacity models to best reflect local behavior and specifies a calibration procedure that uses two gap acceptance parameters: the critical headway and the follow-up headway. This calibration procedure was used in a case study to develop a calibrated HCM model that was based on driver behavior at three single-lane roundabouts in Carmel, Indiana. Both gap acceptance parameters in Carmel were significantly lower than the default values in the HCM 2010. For validation, the calibrated HCM model was compared with the actual 1-min flow rates collected in the field during the congested periods. The calibrated HCM model was consistent with the field conditions for the low to medium circulating flow rates and overestimates the capacity for the high circulating flow rates. Other findings include the impact of exiting traffic, circulating flow rates, degree of saturation, and amount of the gap acceptance data on the calibration results.
To examine associations between caregiving mental or behavioral health outcomes among emerging US adults, defined as persons aged 18 to 25 years.
The study sample included emerging adult respondents ...to the 2015-2017 Behavioral Risk Factor Surveillance System's caregiving module. Exposures were caregiver (n = 3087), expectant caregiver (n = 2303), and noncaregiver (n = 12 216) status. Expectant caregivers were defined as persons not currently providing care but anticipating doing so within the next 2 years. Outcomes included frequent mental distress (FMD), drinking (binge or heavy), and current smoking (cigarette or e-cigarette use). We used robust Poisson regression to calculate adjusted prevalence ratios (APRs) and corresponding 95% confidence intervals (CIs). We adjusted all models for income.
Caregivers had a similar prevalence of FMD when compared with both expectant caregivers (APR = 1.67; 95% CI = 1.28, 2.17) and noncaregivers (APR = 1.50; 95% CI = 1.23, 1.82). Caregivers had a higher prevalence of current cigarette smoking compared with noncaregivers (APR = 1.44; 95% CI = 1.21, 1.71).
Among emerging adults, providing care is associated with poorer mental health. Point estimates looking at FMD were higher when we compared caregivers with expectant caregivers, suggesting a difference in exchangeability between comparison groups.
This study highlights the importance of including emerging adults in caregiving research.
This study examined multiple influences on the use of tobacco by adolescents in China. Using the theory of triadic influences as a guide, we selected interpersonal, attitudinal/cultural, and ...intrapersonal constructs from baseline data to predict adolescent smoking 1 year later. We used prospective data from middle and high school students (N=11,583) and their parents from the China Seven Cities Study, a longitudinal study that is evaluating the effects of changing economic and social factors on health behaviors including tobacco use. A multilevel regression analysis provided some support that each of the influences in the theory of triadic influences affects adolescent smoking in China. After adjusting for important confounders including age, gender, socioeconomic status, and smoking behaviors (lifetime and past 30-day) at baseline, we found significant risk factors within each of the three categories, including interpersonal influences (parental monitoring, good friend smoking, and peer smoking), attitudinal/cultural influences (school academic ranking, initial liking of smoking, and the meaning of smoking), and intrapersonal influences (susceptibility to smoking, and low self-confidence to quit smoking). Results suggest that the etiology of smoking among adolescents in China might be similar to that observed in western countries and that some of the techniques used successfully in prevention programs in those countries might be useful guides when developing prevention programs in China.
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