M. Earl - Academia.edu (original) (raw)
Papers by M. Earl
Physics Letters B, 2002
A number of different fits to solar neutrino mixing and mass square difference were performed usi... more A number of different fits to solar neutrino mixing and mass square difference were performed using 1496 days of Super-Kamiokande-I's solar neutrino data. These data select two allowed areas at large neutrino mixing when combined with either the solar 8 B flux prediction of the standard solar model or the SNO interaction rate measurements. A global fit combining SK data with the solar neutrino interaction rates measured by Homestake, SNO, Gallex/GNO and SAGE prefers a single allowed area, the Large Mixing Angle solution, at the 98.9% confidence level. The mass square difference ∆m 2 between the two mass eigenstates ranges from about 3 to 19 × 10 −5 eV 2 , while the mixing angle θ is in the range of tan 2 θ ≈0.25-0.65.
Physics Letters B, 1998
The flavor ratio of the atmospheric neutrino flux and its zenith angle dependence have been studi... more The flavor ratio of the atmospheric neutrino flux and its zenith angle dependence have been studied in the multi-GeV energy range using an exposure of 25.5 kiloton-years of the Super-Kamiokande detector. By comparing the data to a detailed Monte Carlo simulation, the ratio (µ/e) DAT A /(µ/e) MC was measured to be 0.66 ± 0.06(stat.) ± 0.08(sys.). In addition, a strong distortion in the shape of the µ-like event zenith angle distribution was observed. The ratio of the number of upward to downward µ-like events was found to be 0.52 +0.07 −0.06 (stat.) ± 0.01(sys.), with an expected value of 0.98 ± 0.03(stat.) ± 0.02(sys.), while the same ratio for the e-like events was consistent with unity.
Physical Review Letters, 1998
We present an analysis of atmospheric neutrino data from a 33.0 kton yr (535-day) exposure of the... more We present an analysis of atmospheric neutrino data from a 33.0 kton yr (535-day) exposure of the Super-Kamiokande detector. The data exhibit a zenith angle dependent deficit of muon neutrinos which is inconsistent with expectations based on calculations of the atmospheric neutrino flux. Experimental biases and uncertainties in the prediction of neutrino fluxes and cross sections are unable to explain our observation. The data are consistent, however, with two-flavor n m $ n t oscillations with sin 2 2u . 0.82 and 5 3 10 24 , Dm 2 , 6 3 10 23 eV 2 at 90% confidence level. [S0031-9007(98)06975-0] PACS numbers: 14.60. Pq, 96.40.Tv Atmospheric neutrinos are produced as decay products in hadronic showers resulting from collisions of cosmic rays with nuclei in the upper atmosphere. Production of electron and muon neutrinos is dominated by the processes p 1 ! m 1 1 n m followed by m 1 ! e 1 1 n m 1 n e (and their charge conjugates) giving an expected ratio 1562 0031-9007͞98͞81(8)͞1562(6)$15.00
Physical Review Letters, 2001
We report the result of a search for neutrino oscillations using precise measurements of the reco... more We report the result of a search for neutrino oscillations using precise measurements of the recoil electron energy spectrum and zenith angle variations of the solar neutrino ux from 1258 days of neutrino-electron scattering data in Super-Kamiokande. The absence of signi cant zenith angle variation and spectrum distortion places strong constraints on neutrino mixing and mass di erence in a ux-independent w ay. Using the Super-Kamiokande ux measurement i n addition, two allowed regions at large mixing are found.
Physical Review Letters, 1998
The first results of the solar neutrino flux measurement from Super-Kamiokande are presented. The... more The first results of the solar neutrino flux measurement from Super-Kamiokande are presented. The results shown here are obtained from data taken between 31 May 1996, and 23 June 1997. Using our measurement of recoil electrons with energies above 6.5 MeV, we infer the total flux of 8 B solar neutrinos to be 2.42 6 0.06͑stat͒ 10.10 20.07 ͑syst͒ 3 10 6 cm 22 s 21 . This result is consistent with the Kamiokande measurement and is 36% of the flux predicted by the BP95 solar model. The flux is also measured in 1.5 month subsets and shown to be consistent with a constant rate. [S0031-9007(98)06804-5] PACS numbers: 26.65. + t, 95.85.Ry, 96.40.Tv
![Research paper thumbnail of Publisher's Note: Search for dark matter WIMPs using upward through-going muons in Super-Kamiokande [Phys. Rev. D 70, 083523 (2004)]](https://attachments.academia-assets.com/43396854/thumbnails/1.jpg)
](Physical Review D, 2004
We present the results of indirect searches for Weakly Interacting Massive Particles (WIMPs), wit... more We present the results of indirect searches for Weakly Interacting Massive Particles (WIMPs), with 1679.6 live days of data from the Super-Kamiokande detector using neutrino-induced upward through-going muons. The search is performed by looking for an excess of high energy muon neutrinos from WIMP annihilations in the Sun, the core of the Earth, and the Galactic Center, as compared to the number expected from the atmospheric neutrino background. No statistically significant excess was seen. We calculate the flux limits in various angular cones around each of the above celestial objects. We obtain conservative model-independent upper limits on the WIMP-
Medical Physics, 2003
Treatment verification has been a weak link in external beam radiation therapy. As new and more c... more Treatment verification has been a weak link in external beam radiation therapy. As new and more complicated treatment techniques, such as intensity-modulated radiation therapy ͑IMRT͒, are implemented into clinical practice, verifying the accuracy of treatment delivery becomes increasingly important. Existing methods for treatment verification are highly labor intensive. We have developed a method for verifying the delivery of external beam radiotherapy and implemented the methodology into a system consisting of both hardware and software components. The system uses grayscale images acquired on the treatment machine from the planned treatment beams. From these images, the photon fluence distribution of each beam is derived. These measured photon fluence maps are then used as input to a separate dose calculation engine to compute the delivered absolute dose and the dose distribution in the same patient, assuming that the patient is set up as required by the treatment plan. The dose distribution generated from the measured fluence maps can then be compared to that of the treatment plan. Software tools, such as overlaying isodose curves generated with this method on those imported from the plan, dose difference maps, dose difference volume histograms, and three-dimensional perspective views of the dose differences, have also been developed. The system thus provides a means to verify the dose, the dose prescription, and the monitor units applied. The potential exists with a suitable electronic portal imaging system to reduce the quality assurance efforts, especially for IMRT.
Medical Physics, 2005
We have studied the degree to which beamlet step-size impacts the quality of intensity modulated ... more We have studied the degree to which beamlet step-size impacts the quality of intensity modulated radiation therapy (IMRT) treatment plans. Treatment planning for IMRT begins with the application of a grid that divides each beam's-eye-view of the target into a number of smaller beamlets (pencil beams) of radiation. The total dose is computed as a weighted sum of the dose delivered by the individual beamlets. The width of each beamlet is set to match the width of the corresponding leaf of the multileaf collimator (MLC). The length of each beamlet (beamlet step-size) is parallel to the direction of leaf travel. The beamlet step-size represents the minimum stepping distance of the leaves of the MLC and is typically predetermined by the treatment planning system. This selection imposes an artificial constraint because the leaves of the MLC and the jaws can both move continuously. Removing the constraint can potentially improve the IMRT plan quality. In this study, the optimized results were achieved using an aperture-based inverse planning technique called direct aperture optimization (DAO). We have tested the relationship between pencil beam step-size and plan quality using the American College of Radiology's IMRT test case. For this case, a series of IMRT treatment plans were produced using beamlet step-sizes of 1, 2, 5, and 10 mm. Continuous improvements were seen with each reduction in beamlet step size. The maximum dose to the planning target volume (PTV) was reduced from 134.7% to 121.5% and the mean dose to the organ at risk (OAR) was reduced from 38.5% to 28.2% as the beamlet step-size was reduced from 10 to 1 mm. The smaller pencil beam sizes also led to steeper dose gradients at the junction between the target and the critical structure with gradients of 6.0, 7.6, 8.7, and 9.1 dose%/mm achieved for beamlet step sizes of 10, 5, 2, and 1 mm, respectively.
Medical Physics, 2002
IMRT treatment plans for step-and-shoot delivery have traditionally been produced through the opt... more IMRT treatment plans for step-and-shoot delivery have traditionally been produced through the optimization of intensity distributions ͑or maps͒ for each beam angle. The optimization step is followed by the application of a leaf-sequencing algorithm that translates each intensity map into a set of deliverable aperture shapes. In this article, we introduce an automated planning system in which we bypass the traditional intensity optimization, and instead directly optimize the shapes and the weights of the apertures. We call this approach ''direct aperture optimization.'' This technique allows the user to specify the maximum number of apertures per beam direction, and hence provides significant control over the complexity of the treatment delivery. This is possible because the machine dependent delivery constraints imposed by the MLC are enforced within the aperture optimization algorithm rather than in a separate leaf-sequencing step. The leaf settings and the aperture intensities are optimized simultaneously using a simulated annealing algorithm. We have tested direct aperture optimization on a variety of patient cases using the EGS4/BEAM Monte Carlo package for our dose calculation engine. The results demonstrate that direct aperture optimization can produce highly conformal step-and-shoot treatment plans using only three to five apertures per beam direction. As compared with traditional optimization strategies, our studies demonstrate that direct aperture optimization can result in a significant reduction in both the number of beam segments and the number of monitor units. Direct aperture optimization therefore produces highly efficient treatment deliveries that maintain the full dosimetric benefits of IMRT.
International Journal of Radiation Oncology*Biology*Physics, 2001
The test cases created in the water phantom demonstrated that direct aperture optimization for IM... more The test cases created in the water phantom demonstrated that direct aperture optimization for IMAT is feasible. The aperture shapes are more intuitive than those generated with leaf sequencing algorithms from beam intensity maps. Highly conformal IMAT treatment plans can be developed with two to three apertures per beam angle, resulting in two to three arcs. Since the MLC constraints are incorporated in the optimization, the direct aperture optimization algorithm also provides a solution for "step and shoot" delivery of fixed-beam IMRT treatments.
International Journal of Cancer, 2001
Physics in Medicine and Biology, 2008
Arc-modulated radiation therapy (AMRT) is a novel rotational intensity-modulated radiation therap... more Arc-modulated radiation therapy (AMRT) is a novel rotational intensity-modulated radiation therapy (IMRT) technique developed for a clinical linear accelerator that aims to deliver highly conformal radiation treatment using just one arc of gantry rotation. Compared to fixed-gantry IMRT and the multiple-arc intensity-modulated arc therapy (IMAT) techniques, AMRT promises the same treatment quality with a single-arc delivery. In this paper, we
Physics Letters B, 2002
A number of different fits to solar neutrino mixing and mass square difference were performed usi... more A number of different fits to solar neutrino mixing and mass square difference were performed using 1496 days of Super-Kamiokande-I's solar neutrino data. These data select two allowed areas at large neutrino mixing when combined with either the solar 8 B flux prediction of the standard solar model or the SNO interaction rate measurements. A global fit combining SK data with the solar neutrino interaction rates measured by Homestake, SNO, Gallex/GNO and SAGE prefers a single allowed area, the Large Mixing Angle solution, at the 98.9% confidence level. The mass square difference ∆m 2 between the two mass eigenstates ranges from about 3 to 19 × 10 −5 eV 2 , while the mixing angle θ is in the range of tan 2 θ ≈0.25-0.65.
Physics Letters B, 1998
The flavor ratio of the atmospheric neutrino flux and its zenith angle dependence have been studi... more The flavor ratio of the atmospheric neutrino flux and its zenith angle dependence have been studied in the multi-GeV energy range using an exposure of 25.5 kiloton-years of the Super-Kamiokande detector. By comparing the data to a detailed Monte Carlo simulation, the ratio (µ/e) DAT A /(µ/e) MC was measured to be 0.66 ± 0.06(stat.) ± 0.08(sys.). In addition, a strong distortion in the shape of the µ-like event zenith angle distribution was observed. The ratio of the number of upward to downward µ-like events was found to be 0.52 +0.07 −0.06 (stat.) ± 0.01(sys.), with an expected value of 0.98 ± 0.03(stat.) ± 0.02(sys.), while the same ratio for the e-like events was consistent with unity.
Physical Review Letters, 1998
We present an analysis of atmospheric neutrino data from a 33.0 kton yr (535-day) exposure of the... more We present an analysis of atmospheric neutrino data from a 33.0 kton yr (535-day) exposure of the Super-Kamiokande detector. The data exhibit a zenith angle dependent deficit of muon neutrinos which is inconsistent with expectations based on calculations of the atmospheric neutrino flux. Experimental biases and uncertainties in the prediction of neutrino fluxes and cross sections are unable to explain our observation. The data are consistent, however, with two-flavor n m $ n t oscillations with sin 2 2u . 0.82 and 5 3 10 24 , Dm 2 , 6 3 10 23 eV 2 at 90% confidence level. [S0031-9007(98)06975-0] PACS numbers: 14.60. Pq, 96.40.Tv Atmospheric neutrinos are produced as decay products in hadronic showers resulting from collisions of cosmic rays with nuclei in the upper atmosphere. Production of electron and muon neutrinos is dominated by the processes p 1 ! m 1 1 n m followed by m 1 ! e 1 1 n m 1 n e (and their charge conjugates) giving an expected ratio 1562 0031-9007͞98͞81(8)͞1562(6)$15.00
Physical Review Letters, 2001
We report the result of a search for neutrino oscillations using precise measurements of the reco... more We report the result of a search for neutrino oscillations using precise measurements of the recoil electron energy spectrum and zenith angle variations of the solar neutrino ux from 1258 days of neutrino-electron scattering data in Super-Kamiokande. The absence of signi cant zenith angle variation and spectrum distortion places strong constraints on neutrino mixing and mass di erence in a ux-independent w ay. Using the Super-Kamiokande ux measurement i n addition, two allowed regions at large mixing are found.
Physical Review Letters, 1998
The first results of the solar neutrino flux measurement from Super-Kamiokande are presented. The... more The first results of the solar neutrino flux measurement from Super-Kamiokande are presented. The results shown here are obtained from data taken between 31 May 1996, and 23 June 1997. Using our measurement of recoil electrons with energies above 6.5 MeV, we infer the total flux of 8 B solar neutrinos to be 2.42 6 0.06͑stat͒ 10.10 20.07 ͑syst͒ 3 10 6 cm 22 s 21 . This result is consistent with the Kamiokande measurement and is 36% of the flux predicted by the BP95 solar model. The flux is also measured in 1.5 month subsets and shown to be consistent with a constant rate. [S0031-9007(98)06804-5] PACS numbers: 26.65. + t, 95.85.Ry, 96.40.Tv
Physical Review D, 2004
We present the results of indirect searches for Weakly Interacting Massive Particles (WIMPs), wit... more We present the results of indirect searches for Weakly Interacting Massive Particles (WIMPs), with 1679.6 live days of data from the Super-Kamiokande detector using neutrino-induced upward through-going muons. The search is performed by looking for an excess of high energy muon neutrinos from WIMP annihilations in the Sun, the core of the Earth, and the Galactic Center, as compared to the number expected from the atmospheric neutrino background. No statistically significant excess was seen. We calculate the flux limits in various angular cones around each of the above celestial objects. We obtain conservative model-independent upper limits on the WIMP-
Medical Physics, 2003
Treatment verification has been a weak link in external beam radiation therapy. As new and more c... more Treatment verification has been a weak link in external beam radiation therapy. As new and more complicated treatment techniques, such as intensity-modulated radiation therapy ͑IMRT͒, are implemented into clinical practice, verifying the accuracy of treatment delivery becomes increasingly important. Existing methods for treatment verification are highly labor intensive. We have developed a method for verifying the delivery of external beam radiotherapy and implemented the methodology into a system consisting of both hardware and software components. The system uses grayscale images acquired on the treatment machine from the planned treatment beams. From these images, the photon fluence distribution of each beam is derived. These measured photon fluence maps are then used as input to a separate dose calculation engine to compute the delivered absolute dose and the dose distribution in the same patient, assuming that the patient is set up as required by the treatment plan. The dose distribution generated from the measured fluence maps can then be compared to that of the treatment plan. Software tools, such as overlaying isodose curves generated with this method on those imported from the plan, dose difference maps, dose difference volume histograms, and three-dimensional perspective views of the dose differences, have also been developed. The system thus provides a means to verify the dose, the dose prescription, and the monitor units applied. The potential exists with a suitable electronic portal imaging system to reduce the quality assurance efforts, especially for IMRT.
Medical Physics, 2005
We have studied the degree to which beamlet step-size impacts the quality of intensity modulated ... more We have studied the degree to which beamlet step-size impacts the quality of intensity modulated radiation therapy (IMRT) treatment plans. Treatment planning for IMRT begins with the application of a grid that divides each beam's-eye-view of the target into a number of smaller beamlets (pencil beams) of radiation. The total dose is computed as a weighted sum of the dose delivered by the individual beamlets. The width of each beamlet is set to match the width of the corresponding leaf of the multileaf collimator (MLC). The length of each beamlet (beamlet step-size) is parallel to the direction of leaf travel. The beamlet step-size represents the minimum stepping distance of the leaves of the MLC and is typically predetermined by the treatment planning system. This selection imposes an artificial constraint because the leaves of the MLC and the jaws can both move continuously. Removing the constraint can potentially improve the IMRT plan quality. In this study, the optimized results were achieved using an aperture-based inverse planning technique called direct aperture optimization (DAO). We have tested the relationship between pencil beam step-size and plan quality using the American College of Radiology's IMRT test case. For this case, a series of IMRT treatment plans were produced using beamlet step-sizes of 1, 2, 5, and 10 mm. Continuous improvements were seen with each reduction in beamlet step size. The maximum dose to the planning target volume (PTV) was reduced from 134.7% to 121.5% and the mean dose to the organ at risk (OAR) was reduced from 38.5% to 28.2% as the beamlet step-size was reduced from 10 to 1 mm. The smaller pencil beam sizes also led to steeper dose gradients at the junction between the target and the critical structure with gradients of 6.0, 7.6, 8.7, and 9.1 dose%/mm achieved for beamlet step sizes of 10, 5, 2, and 1 mm, respectively.
Medical Physics, 2002
IMRT treatment plans for step-and-shoot delivery have traditionally been produced through the opt... more IMRT treatment plans for step-and-shoot delivery have traditionally been produced through the optimization of intensity distributions ͑or maps͒ for each beam angle. The optimization step is followed by the application of a leaf-sequencing algorithm that translates each intensity map into a set of deliverable aperture shapes. In this article, we introduce an automated planning system in which we bypass the traditional intensity optimization, and instead directly optimize the shapes and the weights of the apertures. We call this approach ''direct aperture optimization.'' This technique allows the user to specify the maximum number of apertures per beam direction, and hence provides significant control over the complexity of the treatment delivery. This is possible because the machine dependent delivery constraints imposed by the MLC are enforced within the aperture optimization algorithm rather than in a separate leaf-sequencing step. The leaf settings and the aperture intensities are optimized simultaneously using a simulated annealing algorithm. We have tested direct aperture optimization on a variety of patient cases using the EGS4/BEAM Monte Carlo package for our dose calculation engine. The results demonstrate that direct aperture optimization can produce highly conformal step-and-shoot treatment plans using only three to five apertures per beam direction. As compared with traditional optimization strategies, our studies demonstrate that direct aperture optimization can result in a significant reduction in both the number of beam segments and the number of monitor units. Direct aperture optimization therefore produces highly efficient treatment deliveries that maintain the full dosimetric benefits of IMRT.
International Journal of Radiation Oncology*Biology*Physics, 2001
The test cases created in the water phantom demonstrated that direct aperture optimization for IM... more The test cases created in the water phantom demonstrated that direct aperture optimization for IMAT is feasible. The aperture shapes are more intuitive than those generated with leaf sequencing algorithms from beam intensity maps. Highly conformal IMAT treatment plans can be developed with two to three apertures per beam angle, resulting in two to three arcs. Since the MLC constraints are incorporated in the optimization, the direct aperture optimization algorithm also provides a solution for "step and shoot" delivery of fixed-beam IMRT treatments.
International Journal of Cancer, 2001
Physics in Medicine and Biology, 2008
Arc-modulated radiation therapy (AMRT) is a novel rotational intensity-modulated radiation therap... more Arc-modulated radiation therapy (AMRT) is a novel rotational intensity-modulated radiation therapy (IMRT) technique developed for a clinical linear accelerator that aims to deliver highly conformal radiation treatment using just one arc of gantry rotation. Compared to fixed-gantry IMRT and the multiple-arc intensity-modulated arc therapy (IMAT) techniques, AMRT promises the same treatment quality with a single-arc delivery. In this paper, we