Absolute x-ray power measurements with subnanosecond time resolution using type IIa diamond photoconductors

Kania, D. R.; Pan, Lehua; Bell, P.; Landen, O. L.; Kornblum, H. N.; Pianetta, P.; Perry, M. D.

doi:10.1063/1.347104

Cited by 68 publications

(13 citation statements)

References 22 publications

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“…The absorption of electromagnetic waves is characterized by its absorption length which is defined as the distance in which the intensity drops to 1/e of the incident wave. As we know, diamond is transparent for visible light, i.e has an infinite absorption length; while it quickly changes with frequency to be ≈ 0.2 µm for x-rays [33]. Hence the 500 µm of the detector would completely absorb any x-ray produced in a synchrotron radiation.…”

Section: Photon Excitationsmentioning

confidence: 99%

Determination of electron beam polarization using electron detector in Compton polarimeter with less than 1% statistical and systematic uncertainty

Narayan¹

2015

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Title of Study: Determination of electron beam polarization using electron detector inCompton polarimeter with less than 1% statistical and systematic uncertainty Pages of Study: 250Candidate for Degree of Doctor of PhilosophyThe Q-weak experiment aims to measure the weak charge of proton with a precision of 4.2%. The proposed precision on weak charge required a 2.5% measurement of the parity violating asymmetry in elastic electron -proton scattering. Polarimetry was the largest experimental contribution to this uncertainty and a new Compton polarimeter was installed in Hall C at Jefferson Lab to make the goal achievable.In this polarimeter the electron beam collides with green laser light in a low gain FabryPerot Cavity; the scattered electrons are detected in 4 planes of a novel diamond micro strip detector while the back scattered photons are detected in lead tungstate crystals. This diamond micro-strip detector is the first such device to be used as a tracking detector in a nuclear and particle physics experiment. The diamond detectors are read out using custom built electronic modules that include a preamplifier, a pulse shaping amplifier and a discriminator for each detector micro-strip. We use field programmable gate array based general purpose logic modules for event selection and histogramming. Extensive Monte Carlo simulations and data acquisition simulations were performed to estimate the systematic uncertainties. Additionally, the Moller and Compton polarimeters were cross calibrated at low electron beam currents using a series of interleaved measurements. In this dissertation, we describe all the subsystems of the Compton polarimeter with emphasis on the electron detector. We focus on the FPGA based data acquisition system built by the author and the data analysis methods implemented by the author. The simulations of the data acquisition and the polarimeter that helped rigorously establish the systematic uncertainties of the polarimeter are also elaborated, resulting in the first sub 1% measurement of low energy (∼1 GeV) electron beam polarization with a Compton electron detector. We have demonstrated that diamond based micro-strip detectors can be used for tracking in a high radiation environment and it has enabled us to achieve the desired precision in the measurement of the electron beam polarization which in turn has allowed the most precise determination of the weak charge of the proton.

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Section: Photon Excitationsmentioning

confidence: 99%

Determination of electron beam polarization using electron detector in Compton polarimeter with less than 1% statistical and systematic uncertainty

Narayan¹

2015

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“…Diamond has been used as a robust x-ray sensor material for several decades [1][2][3][4]. Its high strength and thermal conductivity make it ideal for high radiation environments.…”

Section: Motivationmentioning

confidence: 99%

Responsivity of Diamond X-ray Photodiodes Calibrated at NSLS

Keister

Smedley

Muller

et al. 2010

AIP Conference Proceedings

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Abstract. Single crystal, high purity synthetic diamond is used as photoabsorption and carrier transport medium in x-ray photodiodes. While the thermal / mechanical robustness and high x-ray transmission of diamond make such devices attractive for synchrotron instrumentation, state-of-the-art quality material and electrical interfaces further make such detectors feasible. The present work develops methodology for attaining calculable responsivity (photocurrent yield) over a wide range of photon energies (0.2 to 28 keV) to within 5% accuracy. These methods achieve linear response for up to 0.2 W absorbed x-ray power and response time as low as 1 ns. Details of contact formation / robustness and bias configuration are explored.

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“…The first pulse consists of 15 beams in cones at angles between 48 and 62 degrees from the normal to the LEH; these beams are the darker shaded outer beams in the geometry shown in Figure 1 Photoconductive Detectors (PCDs) are also used to measure the radiation temperature of the drive. These detectors consist of 1 mm cubes of natural type IIa (insulating) diamond crystal biased to 800 V and become conducting when exposed to an x-ray flux [4]. Provided the carrier density in the diamond produced by the incident xrays is within the desired range, the PCD will produce a linear, flat response with a time response less than 100 ps [5].…”

Section: Description Of Halfraum Experimentsmentioning

confidence: 99%

Measurements and calculations of halfraum radiation drives at the omega laser

MacLaren

Back

Hammer

2006

Journal of Quantitative Spectroscopy and Radiative Transfer

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Thin walled gold halfraums are a common choice for producing x-ray drives in experiments at high-power laser facilities. At the Omega Laser, we use 10 kJ of laser energy in a two-pulse sequence to generate halfraum drive temperatures of 160-190 eV for ~3ns. This type of drive is well characterized and reproducible, with characterization of the drive radiation temperature typically performed using the Dante diagnostic.Additionally, calibrated Photoconductive Diamond Detectors (PCDs) are used to measure the drive when it is desirable to utilize the Dante elsewhere in the experiment.Measurements of halfraum drives from both Dante and PCDs are compared with calculations, with good agreement. This agreement lends the calculations a predictive capability in designing further experiments utilizing halfraum drives.

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Absolute x-ray power measurements with subnanosecond time resolution using type IIa diamond photoconductors

Cited by 68 publications

References 22 publications

Determination of electron beam polarization using electron detector in Compton polarimeter with less than 1% statistical and systematic uncertainty

Determination of electron beam polarization using electron detector in Compton polarimeter with less than 1% statistical and systematic uncertainty

Responsivity of Diamond X-ray Photodiodes Calibrated at NSLS

Measurements and calculations of halfraum radiation drives at the omega laser

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