The front-end of IsoDAR

The Isotope Decay-At-Rest (IsoDAR) experiment is a cyclotron based neutrino oscillation exper- iment that is capable of decisively searching for low-mass sterile neutrinos. This paper outlines two new approaches that the IsoDAR collaboration are pursuing in order to increase the amount of H + 2 captured in the cyclotron through innovations in the design of the front-end. A new dedicated multicusp ion source (MIST-1) is currently being commissioned and tested at the Plasma Science and Fusion Center (PSFC) at MIT. Based on previous results from this type of ion source, we ex- pect to be able to achieve an H+₂ current density that will be sufficient for the IsoDAR experiment. We also discuss the results of a new investigation into using a radio frequency quadrupole (RFQ) as a high-efficiency buncher to improve the injection efficiency into the cyclotron.National Science Foundation (U.S.) (Grant 1505858)National Science Foundation (U.S.) (Grant 1626069

Automated tube potential selection for standard chest and abdominal CT in follow-up patients with testicular cancer: comparison with fixed tube potential

Objective: To evaluate prospectively, in patients with testicular cancer, the radiation dose-saving potential and image quality of contrast-enhanced chest and abdominal CT with automated tube potential selection. Methods: Forty consecutive patients with testicular cancer underwent contrast-enhanced arterio-venous chest and portal-venous abdominal CT with automated tube potential selection (protocol B; tube potential 80-140kVp), which is based on the attenuation of the CT topogram. All had a first CT at 120kVp (protocol A) using the same 64-section CT machine and similar settings. Image quality was assessed; dose information (CTDIvol) was noted. Results: Image noise and attenuation in the liver and spleen were significantly higher for protocol B (P < 0.05 each), whereas attenuation in the deltoid and erector spinae muscles was similar. In protocol B, tube potential was reduced to 100kVp in 18 chest and 33 abdominal examinations, and to 80kVp in 5 abdominal CT examinations; it increased to 140kVp in one patient. Image quality of examinations using both CT protocols was rated as diagnostic. CTDIvol was significantly lower for protocol B compared to protocol A (reduction by 12%, P < 0.01). Conclusion: In patients with testicular cancer, radiation dose of chest and abdominal CT can be reduced with automated tube potential selection, while image quality is preserve

AN RFQ DIRECT INJECTION SCHEME FOR THE ISODAR HIGH INTENSITY H+₂ CYCLOTRON

IsoDAR is a novel experiment designed to measure neutrino oscillations through e disappearance, thus providing a definitive search for sterile neutrinos. In order to generate the necessary anti-neutrino flux, a high intensity primary proton beam is needed. In IsoDAR, H+2 is accelerated and is stripped into protons just before the target, to overcome space charge issues at injection. As part of the design, we have refined an old proposal to use an RFQ to axially inject bunched H+2 ions into the driver cyclotron. This method has several advantages over a classical low energy beam transport (LEBT) design: (1) The bunching efficiency is higher than for the previously considered two-gap buncher and thus the overall injection efficiency is higher. This relaxes the constraints on the H+2 current required from the ion source. (2) The overall length of the LEBT can be reduced. (3) The RFQ can also accelerate the ions. This enables the ion source platform high voltage to be reduced from 70 kV to 30 kV, making underground installation easier. We are presenting the preliminary RFQ design parameters and first beam dynamics simulations from the ion source to the spiral inflector entrance.National Science Foundation (U.S.). Division of Physics (NSF-PHY-1148134)MIT Energy Initiative Seed Fund Progra

Low-dose CT of the lung: potential value of iterative reconstructions

Objectives: To prospectively assess the impact of sinogram-affirmed iterative reconstruction (SAFIRE) on image quality of nonenhanced low-dose lung CT as compared to filtered back projection (FBP). Methods: Nonenhanced low-dose chest CT (tube current-time product: 30mAs) was performed on 30 patients at 100kVp and on 30 patients at 80kVp. Images were reconstructed with FBP and SAFIRE. Two blinded, independent readers measured image noise; two readers assessed image quality of normal anatomic lung structures on a five-point scale. Radiation dose parameters were recorded. Results: Image noise in datasets reconstructed with FBP (57.4 ± 15.9) was significantly higher than with SAFIRE (31.7 ± 9.8, P < 0.001). Image quality was significantly superior with SAFIRE than with FBP (P < 0.01), without significant difference between FBP at 100kVp and SAFIRE at 80kVp (P = 0.68). Diagnostic image quality was present with FBP in 96% of images at 100kVp and 88% at 80kVp, and with SAFIRE in 100% at 100kVp and 98% at 80kVp. There were significantly more datasets with diagnostic image quality with SAFIRE than with FBP (P < 0.01). Mean CTDIvol and effective doses were 1.5 ± 0.7mGy·cm and 0.7 ± 0.2mSv at 100kVp, and 1.4 ± 2.8mGy·cm and 0.5 ± 0.2mSv at 80kVp (P < 0.001, both). Conclusions: Use of SAFIRE in low-dose lung CT reduces noise, improves image quality, and renders more studies diagnostic as compared to FBP. Key Points : • Low-dose computed tomography is an important thoracic investigation tool. • Radiation dose can be less than 1mSv with iterative reconstructions. • Iterative reconstructions render more low-dose lung CTs diagnostic compared to conventional reconstruction

The IsoDAR high intensity H2+ transport and injection tests

This technical report reviews the tests performed at the Best Cyclotron Systems, Inc. facility in regards to developing a cost effective ion source, beam line transport system, and acceleration system capable of high H[subscript 2][superscript +] current output for the IsoDAR (Isotope Decay At Rest) experiment. We begin by outlining the requirements for the IsoDAR experiment then provide overviews of the Versatile Ion Source (VIS), Low Energy Beam Transport (LEBT) system, spiral inflector, and cyclotron. The experimental measurements are then discussed and the results are compared with a thorough set of simulation studies. Of particular importance we note that the VIS proved to be a reliable ion source capable of generating a large amount of H[subscript 2][superscript +] current. The results suggest that with further upgrades, the VIS could potentially be a suitable candidate for IsoDAR. The conclusion outlines the key results from our tests and introduces the forthcoming work this technical report has motivated.National Science Foundation (U.S.) (PHY-1148134)Massachusetts Institute of Technology (Seed Fund)Massachusetts Institute of Technology (Bose Fellowship