This work presents the design and test results of a charged-particle solid-state detector with ultrafast signal response based on polycrystalline chemical-vapor-deposition (pCVD) diamond as active detector material and a high-bandwidth RF amplifier. We tested the detector at the Indiana University Cyclotron Facility Bloomington, IN, in a proton beam with a kinetic energy ranging from 55 to 200 MeV. The detector signals showed an average pulsewidth of 1.38 ns, which enables single-particle counting at instantaneous rates approaching the gigahertz range. The detector operated with a signal-to-noise ratio of 7 : 1 for 200-MeV protons and a single-particle detection efficiency up to 99%.

/pdf/a-fast-low-noise-charged-particle-cvd-diamond-detector-55c7ux3tgf.pdf

A fast low-noise charged-particle CVD diamond detector

http://www-adamas.gsi.de/ADAMAS02/talks/schirru_ADAMAS02_alpha.pdf

Thin single crystal diamond detectors for alpha particle detection

Diamond electronic device exploration began over 70 years ago with evaluations of natural stones for potential use as radiation detectors.1 Often thousands of natural stones were painstakingly evaluated for their “counting” properties in the presence of ionizing radiation.2, 3 Over the years, the electrical, mechanical, optical, and magnetic properties have been studied in natural stones.1 These properties were often found to be superior to those of any other material. The development of synthetic high temperature, high pressure and explosion-based processes for producing synthetic diamonds provided large quantities of similar material beginning in the 1950’s.1 Industrial use of diamonds was primarily limited to cutting and abrasive applications with a few niche applications involving optical windows or heat spreaders.4 Unfortunately, high quality diamond, either naturally occurring or produced synthetically, was still limited to a few square millimeters. Thus, diamond has not found wide acceptance as a material for electronic device fabrication owing to the availability of reproducible high quality large-area, inexpensive material.

Passive Diamond Electronic Devices

In this paper, we present experimental and numerical studies of the signals from the Poisson-like distributions resulting from electrons incident on a diamond sensor placed near the exit of the PHIL photoinjector facility at LAL. The experiments were performed at the newly commissioned Low Energy Electron TECHnology (LEETECH) platform at PHIL. Bunches of 10x9 electrons are first generated and accelerated to 3.5 MeV by PHIL. The electrons are then filtered in LEETECH by a system of collimators, using a dipole magnet for momentum selection. The diamond sensor is located immediately after the output collimator to collect electrons in the range 2.5-3 MeV. We show that with standard scCVD diamonds of 500 micrometers thickness, the energy losses from the first three MIP (minimum ionizing particle) electrons are clearly resolved. We did not observe distinguishable peaks in cases when a significant fraction of the incident electrons had energies below a MIP. The described technique can be used as complementary approach for calibration of diamond detectors as well as to diagnose and help control accelerated beams in a regime down to a few particles.

Diamond Sensor Resolution in Simultaneous Detection of 1,2,3 Electrons at the PHIL Photoinjector Facility at LAL

Following neutron capture in a material there will be prompt nuclear recoils in addition to the gamma cascade. The nuclear recoils that are left behind in materials are generally below 1\,keV and therefore in the range of interest for dark matter experiments and CE$\nu$NS studies--both as backgrounds and calibration opportunities. Here we obtain the spectrum of prompt nuclear recoils following neutron capture for silicon.

Neutron capture-induced silicon nuclear recoils for dark matter and CEνNS

Temporally resolved response of a natural type IIA diamond detector to single-particle excitation

Neutron capture-induced nuclear recoils can create a spectrum that strongly overlaps the CE ν NS signal for nuclear reactor measurements. In this work we show that for these measurements it is critical that the environment be kept below ∼ 10 − 4 n/cm 2 s in eﬀective thermal neutron ﬂux (for a 1 MW reactor at 10 m) so that the CE ν NS events can be measured at least at a 5 σ level. Improved detector resolution can aid the measurement, but the thermal ﬂux is the key parameter. This ﬂux goal is around 10% of the sea-level ﬂux but needs to be achieved in a nominally high-ﬂux (reactor) environment.

Critical background for CE ν NS measurements at reactors

Participants in this workshop will have the opportunity to explore dark matter through scientific literature-based (Fraternali, F. et al., 2011; Jimenez et al., 2003; Karukes, E. V. et al., 2015; Naray et al., 2008; Richards et al., 2015) galactic rotation curves both by using interactive programs and by editing Python code. This will give participants an understanding of how physicists arrived at the idea of dark matter, showing them the difference between curve fits with and without dark matter components. Understanding dark matter’s epistemological origins will help participants formulate their own opinions on the dark matter debate.

The Data Behind Dark Matter: Exploring Galactic Rotation

Nuclear reactors represent a promising neutrino source for $\mathrm{CE}\ensuremath{\nu}\mathrm{NS}$ (coherent-elastic neutrino-nucleus scattering) searches. However, reactor sites also come with high ambient neutron flux. Neutron capture-induced nuclear recoils can create a spectrum that strongly overlaps the $\mathrm{CE}\ensuremath{\nu}\mathrm{NS}$ signal for recoils $\ensuremath{\lesssim}100\text{ }\text{ }\mathrm{eV}$ for nuclear reactor measurements in silicon or germanium detectors. This background can be particularly critical for low-power research reactors providing a moderate neutrino flux. In this work we quantify the impact of this background and show that, for a measurement 10 m from a 1 MW reactor, the effective thermal neutron flux should be kept below $\ensuremath{\sim}7\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}\text{ }\text{ }\mathrm{n}/{\mathrm{cm}}^{2}\text{ }\mathrm{s}$ so that the $\mathrm{CE}\ensuremath{\nu}\mathrm{NS}$ events can be measured at least at a $5\ensuremath{\sigma}$ level with germanium detectors in 100 kg yr exposure time. This flux corresponds to 60% of the sea-level flux but needs to be achieved in a nominally high-flux (reactor) environment. Improved detector resolution can help the measurements, but the thermal flux is the key parameter for the sensitivity of the experiment. For silicon detectors, the constraint is even stronger and thermal neutron fluxes must be near an order of magnitude lower. This constraint highlights the need of an effective thermal neutron mitigation strategy for future low threshold $\mathrm{CE}\ensuremath{\nu}\mathrm{NS}$ searches. In particular, the neutron capture-induced background can be efficiently reduced by active veto systems tagging the deexcitation gamma following the capture. 

/pdf/neutron-capture-induced-nuclear-recoils-as-background-for-2yiwyi62.pdf

Neutron capture-induced nuclear recoils as background for 
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi>CE</mml:mi><mml:mi>ν</mml:mi><mml:mi>NS</mml:mi></mml:mrow></mml:math>
 measurements at reactors

K. Harris

Papers

Temporally resolved response of a natural type IIA diamond detector to single-particle excitation

Neutron capture-induced silicon nuclear recoils for dark matter and CEνNS

Critical background for CE ν NS measurements at reactors

The Data Behind Dark Matter: Exploring Galactic Rotation

Neutron capture-induced nuclear recoils as background for <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi>CE</mml:mi><mml:mi>ν</mml:mi><mml:mi>NS</mml:mi></mml:mrow></mml:math> measurements at reactors