Global kidney exchange : opportunity or exploitation? An ELPAT/ESOT appraisal

This paper addresses ethical, legal, and psychosocial aspects of Global Kidney Exchange (GKE). Concerns have been raised that GKE violates the nonpayment principle, exploits donors in low‐ and middle‐income countries, and detracts from the aim of self‐sufficiency. We review the arguments for and against GKE. We argue that while some concerns about GKE are justified based on the available evidence, others are speculative and do not apply exclusively to GKE but to living donation more generally. We posit that concerns can be mitigated by implementing safeguards, by developing minimum quality criteria and by establishing an international committee that independently monitors and evaluates GKE’s procedures and outcomes. Several questions remain however that warrant further clarification. What are the experiences and views of recipients and donors participating in GKE? Who manages the escrow funds that have been put in place for donor and recipients? What procedures and safeguards have been put in place to prevent corruption of these funds? What are the inclusion criteria for participating GKE centers? GKE provides opportunity to promote access to donation and transplantation but can only be conducted with the appropriate safeguards. Patients’ and donors’ voices are missing in this debate

Global Kidney Exchange: opportunity or exploitation? An ELPAT/ESOT appraisal

This paper addresses ethical, legal, and psychosocial aspects of Global Kidney Exchange (GKE). Concerns have been raised that GKE violates the nonpayment principle, exploits donors in low- and middle-income countries, and detracts from the aim of self-sufficiency. We review the arguments for and against GKE. We argue that while some concerns about GKE are justified based on the available evidence, others are speculative and do not apply exclusively to GKE but to living donation more generally. We posit that concerns can be mitigated by implementing safeguards, by developing minimum quality criteria and by establishing an international committee that independently monitors and evaluates GKE’s procedures and outcomes. Several questions remain however that warrant further clarificati

Raising awareness of unspecified living kidney donation: An ELPAT

Background: Living donor kidney transplantation (LDKT) is the preferred treatment for patients with end-stage renal disease and unspecified living kidney donation is morally justified. Despite the excellent outcomes of LDKT, unspecified kidney donation (UKD) is limited to a minority of European countries due to legal constraints and moral objections. Consequently, there are significant variations in practice and approach between countries and the contribution of UKD is undervalued. Where UKD is accepted as routine, an increasing number of patients in the kidney exchange programme are successfully transplanted when a 'chain' of transplants is triggered by a single unspecified donor. By expanding the shared living donor pool, the benefit of LDKT is extended to patients who do not have their own living donor because a recipient on the national transplant list always completes the chain. Is there a moral imperative to increase the scope of UKD and how could this be achieved? Methods: An examination of the literature and individual country practices was performed to identify the limitations on UKD in Europe and recommend strategies to increase transplant opportunities. Results: Primary limitations to UKD, key players and their roles and responsibilities were identified. Conclusions: Raising awareness to encourage the public to volunteer to donate is appropriate and desirable to increase UKD. Recommendations are made to provide a framework for increasing awareness and engagement in UKD. The public, healthcare professionals, policy makers and society and religious leaders have a role to play in creating an environment for change

Study of cosmogenic activation above ground for the DarkSide-20k experiment

The activation of materials due to exposure to cosmic rays may become an important background source for experiments investigating rare event phenomena. DarkSide-20k, currently under construction at the Laboratori Nazionali del Gran Sasso, is a direct detection experiment for galactic dark matter particles, using a two-phase liquid-argon Time Projection Chamber (TPC) filled with 49.7 tonnes (active mass) of Underground Argon (UAr) depleted in 39Ar. Despite the outstanding capability of discriminating / background in argon TPCs, this background must be considered because of induced dead time or accidental coincidences mimicking dark-matter signals and it is relevant for low-threshold electron-counting measurements. Here, the cosmogenic activity of relevant long-lived radioisotopes induced in the experiment has been estimated to set requirements and procedures during preparation of the experiment and to check that it is not dominant over primordial radioactivity; particular attention has been paid to the activation of the 120 t of UAr used in DarkSide-20k. Expected exposures above ground and production rates, either measured or calculated, have been considered in detail. From the simulated counting rates in the detector due to cosmogenic isotopes, it is concluded that activation in copper and stainless steel is not problematic. The activity of 39Ar induced during extraction, purification and transport on surface is evaluated to be 2.8% of the activity measured in UAr by DarkSide-50 experiment, which used the same underground source, and thus considered acceptable. Other isotopes in the UAr such as 37Ar and 3H are shown not to be relevant due to short half-life and assumed purification methods

Measurement of isotopic separation of argon with the prototype of the cryogenic distillation plant Aria for dark matter searches

The Aria cryogenic distillation plant, located in Sardinia, Italy, is a key component of the DarkSide-20k experimental program for WIMP dark matter searches at the INFN Laboratori Nazionali del Gran Sasso, Italy. Aria is designed to purify the argon, extracted from underground wells in Colorado, USA, and used as the DarkSide-20k target material, to detector-grade quality. In this paper, we report the first measurement of argon isotopic separation by distillation with the 26 m tall Aria prototype. We discuss the measurement of the operating parameters of the column and the observation of the simultaneous separation of the three stable argon isotopes: 36Ar , 38Ar , and 40Ar . We also provide a detailed comparison of the experimental results with commercial process simulation software. This measurement of isotopic separation of argon is a significant achievement for the project, building on the success of the initial demonstration of isotopic separation of nitrogen using the same equipment in 2019

Study on cosmogenic activation above ground for the DarkSide-20k project

The activation of materials due to the exposure to cosmic rays may become an important background source for experiments investigating rare event phenomena. DarkSide-20k is a direct detection experiment for galactic dark matter particles, using a two-phase liquid argon time projection chamber filled with 49.7 tonnes (active mass) of Underground Argon (UAr) depleted in 39Ar. Here, the cosmogenic activity of relevant long-lived radioisotopes induced in the argon and other massive components of the set-up has been estimated; production of 120 t of radiopure UAr is foreseen. The expected exposure above ground and production rates, either measured or calculated, have been considered. From the simulated counting rates in the detector due to cosmogenic isotopes, it is concluded that activation in copper and stainless steel is not problematic. Activation of titanium, considered in early designs but not used in the final design, is discussed. The activity of 39Ar induced during extraction, purification and transport on surface, in baseline conditions, is evaluated to be 2.8% of the activity measured in UAr from the same source, and thus considered acceptable. Other products in the UAr such as 37Ar and 3H are shown to not be relevant due to short half-life and assumed purification methods

Directionality of nuclear recoils in a liquid argon time projection chamber

The direct search for dark matter in the form of weakly interacting massive particles (WIMP) is performed by detecting nuclear recoils (NR) produced in a target material from the WIMP elastic scattering. A promising experimental strategy for direct dark matter search employs argon dual-phase time projection chambers (TPC). One of the advantages of the TPC is the capability to detect both the scintillation and charge signals produced by NRs. Furthermore, the existence of a drift electric field in the TPC breaks the rotational symmetry: the angle between the drift field and the momentum of the recoiling nucleus can potentially affect the charge recombination probability in liquid argon and then the relative balance between the two signal channels. This fact could make the detector sensitive to the directionality of the WIMP-induced signal, enabling unmistakable annual and daily modulation signatures for future searches aiming for discovery. The Recoil Directionality (ReD) experiment was designed to probe for such directional sensitivity. The TPC of ReD was irradiated with neutrons at the INFN Laboratori Nazionali del Sud, and data were taken with 72 keV NRs of known recoil directions. The direction-dependent liquid argon charge recombination model by Cataudella et al. was adopted and a likelihood statistical analysis was performed, which gave no indications of significant dependence of the detector response to the recoil direction. The aspect ratio R of the initial ionization cloud is estimated to be 1.037 +/- 0.027 and the upper limit is R < 1.072 with 90% confidence levelComment: 20 pages, 10 figures, submitted to Eur. Phys. J.