Performance of HPGe Detectors in High Magnetic Fields

A new generation of high-resolution hypernuclear gamma$-spectroscopy experiments with high-purity germanium detectors (HPGe) are presently designed at the FINUDA spectrometer at DAPhiNE, the Frascati phi-factory, and at PANDA, the antiproton proton hadron spectrometer at the future FAIR facility. Both, the FINUDA and PANDA spectrometers are built around the target region covering a large solid angle. To maximise the detection efficiency the HPGe detectors have to be located near the target, and therefore they have to be operated in strong magnetic fields B ~ 1 T. The performance of HPGe detectors in such an environment has not been well investigated so far. In the present work VEGA and EUROBALL Cluster HPGe detectors were tested in the field provided by the ALADiN magnet at GSI. No significant degradation of the energy resolution was found, and a change in the rise time distribution of the pulses from preamplifiers was observed. A correlation between rise time and pulse height was observed and is used to correct the measured energy, recovering the energy resolution almost completely. Moreover, no problems in the electronics due to the magnetic field were observed.Comment: submitted to Nucl. Instrum. Meth. Phys. Res. A, LaTeX, 19 pages, 9 figure

Burden and resources in caregivers of people with multiple sclerosis: A qualitative study

Background Caregivers of people with Multiple Sclerosis are required to provide ongoing assistance especially during the advanced stages of the disease. They have to manage interventions and assume responsibilities which significantly impact both their personal quality of life and family’s dynamics. Objective A qualitative phenomenological study was carried out to understand the experience of burden in caregivers and their resources to manage it. The study also explores how healthcare services involved in the Multiple Sclerosis Clinical Pathway respond to the needs of wellbeing of patients and family members. Methods 17 caregivers were involved in focus groups and in semi-structured individual interviews. Results Fatigue is experienced by all respondents and it starts when physical disabilities increase or when people become aware of them. Many caregivers declare that they refer to intrinsic (love towards their relatives, patience and dedication) or extrinsic (family members, hobbies) resources to cope with the burden of assistance. Patient associations and the Multiple Sclerosis Clinical Pathway play a significant role in supporting caregivers. Conclusions Fatigue, loneliness, and isolation are experienced by caregivers and strongly affect their quality of life and health status. The study highlights caregivers’ need to reconcile working times with care times, to give more space to self-care and to have moments to share their experiences with someone else. These needs should be at the core of health policies in order to avoid physical and emotional breakdowns which could lead to the rupture of the relational balance on which home care is based

A hybrid radiation detector for simultaneous spatial and temporal dosimetry

In this feasibility study an organic plastic scintillator is calibrated against ionisation chamber measurements and then embedded in a polymer gel dosimeter to obtain a quasi-4D experimental measurement of a radiation field. This hybrid dosimeter was irradiated with a linear accelerator, with temporal measurements of the dose rate being acquired by the scintillator and spatial measurements acquired with the gel dosimeter. The detectors employed in this work are radiologically equivalent; and we show that neither detector perturbs the intensity of the radiation field of the other. By employing these detectors in concert, spatial and temporal variations in the radiation intensity can now be detected and gel dosimeters can be calibrated for absolute dose from a single irradiation

Auditory laterality in a nocturnal, fossorial marsupial (Lasiorhinus latifrons) in response to bilateral stimuli

Behavioural lateralisation is evident across most animal taxa, although few marsupial and no fossorial species have been studied. Twelve wombats (Lasiorhinus latifrons) were bilaterally presented with eight sounds from different contexts (threat, neutral, food) to test for auditory laterality. Head turns were recorded prior to and immediately following sound presentation. Behaviour was recorded for 150 seconds after presentation. Although sound differentiation was evident by the amount of exploration, vigilance and grooming performed after different sound types, this did not result in different patterns of head turn direction. Similarly, left-right proportions of head turns, walking events and food approaches in the post-sound period were comparable across sound types. A comparison of head turns performed before and after sound showed a significant change in turn direction (χ2 1 = 10.65, P = 0.001) from a left preference during the pre-sound period (mean 58% left head turns, CI 49-66%) to a right preference in the post-sound (mean 43% left head turns, CI 40-45%). This provides evidence of a right auditory bias in response to the presentation of the sound. This study therefore demonstrates that laterality is evident in southern hairy-nosed wombats in response to a sound stimulus, although side biases were not altered by sounds of varying context

The Gastropack Access System as a Model to Access Gastroenterology Services for Gastroscopy Appropriateness in Patients with Upper Gastrointestinal Symptoms: A Comparison with the Open Access System

Esophagogastroduodenoscopy (EGD) appropriateness in Open-Access System (OAS) is a relevant issue. The Gastropack Access System (GAS) is a new system to access gastroenterological services, based on the partnership between Gastroenterologists and GPs. This study aims to evaluate if GAS is superior to OAS in terms of EGDS appropriateness. Secondarily, we evaluated the diagnostic yield of EGDS according to ASGE guidelines. The GAS was developed in an area of Bologna where General Practitioners (GPs) could decide to directly prescribe EGDS through OAS or referring to GAS, where EGDS can be scheduled after contact between GPs and specialists sharing a patient’s clinical information. Between 2016 and 2019, 2179 cases (M:F = 861:1318, median age 61, IQR 47.72) were referred to GAS and 1467 patients (65%) had a prescription for EGDS; conversely, 874 EGDS were prescribed through OAS (M:F = 383:491; median age 58 yrs, IQR 45.68). Indication was appropriate in 92% in GAS (1312/1424) versus 71% in OAS (618/874), p < 0.001. The rate of clinically significant endoscopic findings (CSEF) was significantly higher in GAS (49% vs. 34.8%, p < 0.001). Adherence to ASGE guidelines was not related to CSEF; however, surveillance for pre-malignant conditions was independently related to CSEF. All neoplasm were observed in appropriate EGD. GAS is an innovative method showing extremely high rates of appropriateness. ASGE guidelines confirmed their validity for cancer detection, but their performance for the detection of other conditions needs to be refined

Gamma-ray Tracking with Segmented HPGe Detectors

This paper gives a brief overview of the technical progress that can be achieved with the newly available segmented HPGe detectors. Gamma-ray tracking detectors are a new generation of HPGe detectors which are currently being developed to improve significantly the efficiency and resolving power of the 4 … germanium detectors arrays for high-precision ∞-ray spectroscopy. They consist of highly segmented HPGe detectors associated with fast digital front-end electronics. Through the pulse-shape analysis of the signals it is possible to extract the energy, timing and spatial information on the few interactions a ∞-ray undergoes in the HPGe detector. The tracks of the ∞-rays in the HPGe detector can then be reconstructed in three dimensions based on the Compton scattering formula. Such a detector has been used for the first time during an in-beam experiment. The ∞-decay of the Coulomb excitation of a 56 Fe nucleus was measured with the highly segmented MARS prototype positioned at 135 degree. The energy resolution has been improved by a factor of 3 as compared to standard HPGe detectors due to very precise Doppler correction based on knowledge of the ∞-ray track. I Introduction The future facilities for radioactive beams will allow, for the first time, the exploration of a new large area of the nuclear landscape. In connection with the study of the ∞-radiation, it is important to point out that the intensity of such radioactive beams is expected to be much smaller than that of stable beams, Doppler Effects in many experiments are expected to be much stronger and an intense background of X-rays could be present. Consequently, a new generation of powerful HPGe arrays with segmented detectors is being designed. Both in USA and in Europe several projects, based on segmented HPGe detectors, have already started and are in an advanced status of realization. The objective of the more recent R&D efforts is to improve the total efficiency by removing the BGO shields without affecting the P/T ratio with the use of the tracking technique, namely the reconstruction of the ∞-ray path to identify the ∞-incident direction (for the Doppler correction), the removal of the background and to check whether or not the ∞ was fully absorbed in the array. Such development implies unprecedented R&D efforts where completely new technology has to be applied, tested or developed in all the constituents of an HPGe array, from the detector to the front-end electronics. The typical feature of the energy deposition of a ∞-ray is that of interacting in a limited number of positions. ∞-tracking of this hits is a very challenging and ambitious task. First, one has to identify, isolate and localize each hit inside a segmented detector with pulse shape analysis based on the study of the physical mechanism of the pulse generation or with Artificial Intelligence techniques (like Neural Networks or Genetic Algorithm [1]) of the direct and induced electrical pulses produced by every interacting ∞-rays. Second, a tracking algorithm has to reconstruct the real trajectory from the list of interaction points through statistical techniques. The result is expected to be the complete reconstruction of the track of the incident ∞, namely the complete description of the interacting ∞-ray. Worldwide efforts have been done using simulations and proof-of-principle measurements and turned out to be successful. The feasibility of the entire process of ∞ray tracking is demonstrated in this paper based on an experiment, done at the LNL in Italy, using the MARS prototype detector

Deducing the \u3csup\u3e237\u3c/sup\u3eU(\u3cem\u3en,f\u3c/em\u3e) Cross Section Using the Surrogate Ratio Method

We have deduced the cross section for 237U(n, f) over an equivalent neutron energy range from 0 to 20 MeV using the surrogate ratio method. A 55 MeV4He beam from the 88 inch cyclotron at Lawrence Berkeley National Laboratory was used to induce fission in the following reactions: 238U(α, αf) and 236U(α, αf). The 238U reaction was a surrogate for 237U(n, f), and the 236U reaction was used as a surrogate for 235U(n, f). Scattered α particles were detected in a fully depleted segmented silicon telescope array over an angle range of 35° to 60° with respect to the beam axis. The fission fragments were detected in a third independent silicon detector located at backward angles between 106° and 131°