Pub Date : 2005-12-01DOI: 10.1109/NSSMIC.2005.1596770
V. Sossi, H. de Jong, W. Barker, P. Bloomfield, Z. Burbar, M. Camborde, C. Comtat, L. Eriksson, S. Houle, D. Keator, C. Knob, R. Krais, A. Lammertsma, A. Rahmim, M. Sibomana, M. Teras, C. Thompson, R. Trébossen, J. Votaw, M. Walker, K. Wienhard, D. Wong
The high resolution research tomograph (HRRT) is one of the most complex existing positron emission tomographs: it is the only human size scanner capable of decoding the depth of the /spl gamma/-ray interaction in the crystal, using a lutetium LSO/LYSO phoswich detector arrangement. In this study we determined basic scanner hardware characteristics, such as scanner data acquisition stability, and their variability across eleven centres. In addition a subset of the NEMA NU-2001 standards measurements was performed. We found (i) significant variability in the DOI decoding results between centres, (ii) a trend toward an increasing number of detected true coincident events as a function of elapsed time from scanner calibration likely due to a shifting energy spectrum, (iii) a count-rate dependent layer identification, (iv) scatter fraction ranging from /spl sim/ 42% to 54% where the variability was partly related to the shifting of the energy spectrum, (v) sensitivity ranging from /spl sim/5.5% to 6.5% across centres, (vi) resolution of /spl sim/(2.5 mm)/sup 3/, fairly consistent across centres, (vii) image quality which is very comparable to other scanners.
{"title":"The second generation HRRT - a multi-centre scanner performance investigation","authors":"V. Sossi, H. de Jong, W. Barker, P. Bloomfield, Z. Burbar, M. Camborde, C. Comtat, L. Eriksson, S. Houle, D. Keator, C. Knob, R. Krais, A. Lammertsma, A. Rahmim, M. Sibomana, M. Teras, C. Thompson, R. Trébossen, J. Votaw, M. Walker, K. Wienhard, D. Wong","doi":"10.1109/NSSMIC.2005.1596770","DOIUrl":"https://doi.org/10.1109/NSSMIC.2005.1596770","url":null,"abstract":"The high resolution research tomograph (HRRT) is one of the most complex existing positron emission tomographs: it is the only human size scanner capable of decoding the depth of the /spl gamma/-ray interaction in the crystal, using a lutetium LSO/LYSO phoswich detector arrangement. In this study we determined basic scanner hardware characteristics, such as scanner data acquisition stability, and their variability across eleven centres. In addition a subset of the NEMA NU-2001 standards measurements was performed. We found (i) significant variability in the DOI decoding results between centres, (ii) a trend toward an increasing number of detected true coincident events as a function of elapsed time from scanner calibration likely due to a shifting energy spectrum, (iii) a count-rate dependent layer identification, (iv) scatter fraction ranging from /spl sim/ 42% to 54% where the variability was partly related to the shifting of the energy spectrum, (v) sensitivity ranging from /spl sim/5.5% to 6.5% across centres, (vi) resolution of /spl sim/(2.5 mm)/sup 3/, fairly consistent across centres, (vii) image quality which is very comparable to other scanners.","PeriodicalId":105619,"journal":{"name":"IEEE Nuclear Science Symposium Conference Record, 2005","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121800728","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-11-25DOI: 10.1109/NSSMIC.2005.1596972
I. Rodionov, J. Bidault, I. Crotty, P. Fonte, F. Galy, V. Peskov, O. Zanette
Hyperspectroscopy is a new method of surface image taking, providing simultaneously high position and spectral resolutions which allow one to make some conclusions about chemical compositions of the surfaces. For image taking advanced MCPs are currently used, sensitive in the spectral interval of 450-850 nm. One of the aims of this work is to extend the hyperspectroscopic method to the UV region of spectra: 185-280 nm. For this we have developed and successfully tested innovative 1D and 2D UV sealed photosensitive gaseous detectors with resistive electrodes. These detectors are superior MCPs due to the very low rate of noise pulses and thus due to the high signal to noise ratio. Other important features of these detectors are that they have excellent position resolutions - 30 mum in digital form, are vibration stable and are spark protected. The first results from the application of these detectors for spectroscopy, hyperspectroscopy and the flame detection are presented
{"title":"Advanced gaseous photodetectors for hyperspectroscopy and other applications","authors":"I. Rodionov, J. Bidault, I. Crotty, P. Fonte, F. Galy, V. Peskov, O. Zanette","doi":"10.1109/NSSMIC.2005.1596972","DOIUrl":"https://doi.org/10.1109/NSSMIC.2005.1596972","url":null,"abstract":"Hyperspectroscopy is a new method of surface image taking, providing simultaneously high position and spectral resolutions which allow one to make some conclusions about chemical compositions of the surfaces. For image taking advanced MCPs are currently used, sensitive in the spectral interval of 450-850 nm. One of the aims of this work is to extend the hyperspectroscopic method to the UV region of spectra: 185-280 nm. For this we have developed and successfully tested innovative 1D and 2D UV sealed photosensitive gaseous detectors with resistive electrodes. These detectors are superior MCPs due to the very low rate of noise pulses and thus due to the high signal to noise ratio. Other important features of these detectors are that they have excellent position resolutions - 30 mum in digital form, are vibration stable and are spark protected. The first results from the application of these detectors for spectroscopy, hyperspectroscopy and the flame detection are presented","PeriodicalId":105619,"journal":{"name":"IEEE Nuclear Science Symposium Conference Record, 2005","volume":"154 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127226135","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-11-14DOI: 10.1109/NSSMIC.2005.1596436
R. Kotthaus, H. Bräuninger, P. Friedrich, R. Hartmann, D. Kang, M. Kuster, Gerhard Lutz, L. Struder
The CERN Axion Solar Telescope (CAST) searches for solar axions employing a 9 tesla superconducting dipole magnet equipped with 3 independent detection systems for X-rays from axion-photon conversions inside the 10 m long magnetic field. Results of the first 6 months of data taking in 2003 imply a 95% CL upper limit on the axion-photon coupling constant of gagamma < 1.16times10-10 GeV-1 for axion masses ma < 0.02 eV. The most sensitive detector of CAST is an X-ray telescope consisting of a Wolter I type mirror system and a fully depleted pn-CCD as focal plane detector. Exploiting the full potential of background suppression by focussing X-rays emerging from the magnet bore, the axion sensitivity obtained with telescope data taken in 2004, for the first time in a controlled laboratory experiment, will supersede axion constraints derived from stellar energy loss arguments
{"title":"The X-ray telescope of the CAST experiment","authors":"R. Kotthaus, H. Bräuninger, P. Friedrich, R. Hartmann, D. Kang, M. Kuster, Gerhard Lutz, L. Struder","doi":"10.1109/NSSMIC.2005.1596436","DOIUrl":"https://doi.org/10.1109/NSSMIC.2005.1596436","url":null,"abstract":"The CERN Axion Solar Telescope (CAST) searches for solar axions employing a 9 tesla superconducting dipole magnet equipped with 3 independent detection systems for X-rays from axion-photon conversions inside the 10 m long magnetic field. Results of the first 6 months of data taking in 2003 imply a 95% CL upper limit on the axion-photon coupling constant of gagamma < 1.16times10-10 GeV-1 for axion masses ma < 0.02 eV. The most sensitive detector of CAST is an X-ray telescope consisting of a Wolter I type mirror system and a fully depleted pn-CCD as focal plane detector. Exploiting the full potential of background suppression by focussing X-rays emerging from the magnet bore, the axion sensitivity obtained with telescope data taken in 2004, for the first time in a controlled laboratory experiment, will supersede axion constraints derived from stellar energy loss arguments","PeriodicalId":105619,"journal":{"name":"IEEE Nuclear Science Symposium Conference Record, 2005","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125273345","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-11-11DOI: 10.1109/NSSMIC.2005.1596615
J. Huber, W. Choong, W. Moses, J. Qi, J. Hu, G. Wang, D. Wilson, S. Oh, R. Huesman, S. Derenzo
We present the characterization of a positron emission tomograph for prostate imaging that centers a patient between a pair of external curved detector banks (ellipse: 45 cm minor, 70 cm major axis). The distance between detector banks adjusts to allow patient access and to position the detectors as closely as possible for maximum sensitivity with patients of various sizes. Each bank is composed of two axial rows of 20 HR+ block detectors for a total of 80 detectors in the camera. The individual detectors are angled in the transaxial plane to point towards the prostate to reduce resolution degradation in that region. The detectors are read out by modified HRRT data acquisition electronics. Compared to a standard whole-body PET camera, our dedicated-prostate camera has the same sensitivity and resolution, less background (less randoms and lower scatter fraction) and a lower cost. We have completed construction of the camera. Characterization data and reconstructed images of several phantoms are shown. Sensitivity of a point source in the center is 946 cps/muCi. Spatial resolution is 4 mm FWHM in the central region
{"title":"Characterization of a PET camera optimized for prostate imaging","authors":"J. Huber, W. Choong, W. Moses, J. Qi, J. Hu, G. Wang, D. Wilson, S. Oh, R. Huesman, S. Derenzo","doi":"10.1109/NSSMIC.2005.1596615","DOIUrl":"https://doi.org/10.1109/NSSMIC.2005.1596615","url":null,"abstract":"We present the characterization of a positron emission tomograph for prostate imaging that centers a patient between a pair of external curved detector banks (ellipse: 45 cm minor, 70 cm major axis). The distance between detector banks adjusts to allow patient access and to position the detectors as closely as possible for maximum sensitivity with patients of various sizes. Each bank is composed of two axial rows of 20 HR+ block detectors for a total of 80 detectors in the camera. The individual detectors are angled in the transaxial plane to point towards the prostate to reduce resolution degradation in that region. The detectors are read out by modified HRRT data acquisition electronics. Compared to a standard whole-body PET camera, our dedicated-prostate camera has the same sensitivity and resolution, less background (less randoms and lower scatter fraction) and a lower cost. We have completed construction of the camera. Characterization data and reconstructed images of several phantoms are shown. Sensitivity of a point source in the center is 946 cps/muCi. Spatial resolution is 4 mm FWHM in the central region","PeriodicalId":105619,"journal":{"name":"IEEE Nuclear Science Symposium Conference Record, 2005","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125960667","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-11-11DOI: 10.1109/NSSMIC.2005.1596768
J. Huber, W. Moses, J. Pouliot, I. Hsu
Functional imaging with positron emission tomography (PET) will detect malignant tumors in the prostate and/or prostate bed, as well as possibly help determine tumor "aggressiveness." However, the relative uptake in a prostate tumor can be so great that few other anatomical landmarks are visible in a PET image. Ultrasound imaging with a transrectal probe provides anatomical detail in the prostate region that can be co-registered with the sensitive functional information from the PET imaging. Imaging the prostate with both PET and transrectal ultrasound (TRUS) will help determine the location of any cancer within the prostate region. This dual-modality imaging should help provide better detection and treatment of prostate cancer. LBNL has built a high performance positron emission tomograph optimized to image the prostate. Compared to a standard whole-body PET camera, our prostate-optimized PET camera has the same sensitivity and resolution, less backgrounds and lower cost. We plan to develop the hardware and software tools needed for a validated dual PET/TRUS prostate imaging system. We also plan to develop dual prostate imaging with PET and external transabdominal ultrasound, in case the TRUS system is too uncomfortable for some patients. We present the design and intended clinical uses for these dual imaging systems.
{"title":"Dual-modality PET/ultrasound imaging of the prostate","authors":"J. Huber, W. Moses, J. Pouliot, I. Hsu","doi":"10.1109/NSSMIC.2005.1596768","DOIUrl":"https://doi.org/10.1109/NSSMIC.2005.1596768","url":null,"abstract":"Functional imaging with positron emission tomography (PET) will detect malignant tumors in the prostate and/or prostate bed, as well as possibly help determine tumor \"aggressiveness.\" However, the relative uptake in a prostate tumor can be so great that few other anatomical landmarks are visible in a PET image. Ultrasound imaging with a transrectal probe provides anatomical detail in the prostate region that can be co-registered with the sensitive functional information from the PET imaging. Imaging the prostate with both PET and transrectal ultrasound (TRUS) will help determine the location of any cancer within the prostate region. This dual-modality imaging should help provide better detection and treatment of prostate cancer. LBNL has built a high performance positron emission tomograph optimized to image the prostate. Compared to a standard whole-body PET camera, our prostate-optimized PET camera has the same sensitivity and resolution, less backgrounds and lower cost. We plan to develop the hardware and software tools needed for a validated dual PET/TRUS prostate imaging system. We also plan to develop dual prostate imaging with PET and external transabdominal ultrasound, in case the TRUS system is too uncomfortable for some patients. We present the design and intended clinical uses for these dual imaging systems.","PeriodicalId":105619,"journal":{"name":"IEEE Nuclear Science Symposium Conference Record, 2005","volume":"05 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128773907","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-11-10DOI: 10.1109/NSSMIC.2005.1596232
R. Chandrasekharan, A. Knecht, M. Messina, C. Regenfus, A. Rubbia
The possibility of efficient collection and detection of vacuum ultraviolet light as emitted by argon, krypton, and xenon gas is studied. Absolute quantum efficiencies of large area avalanche photodiodes (LAAPDs) are derived at these wavelengths. VUV light of wavelengths down to the 128 nm of Ar emission is shown to be detectable with silicon avalanche photodiodes at quantum efficiencies above 42%. Flexible Mylar foil overcoated with Al+MgF2 is measured to have a specular reflectivity of ~91% at argon emission wavelength. Low-pressure argon gas is shown to emit significant amounts of non-UV radiation. The average energy expenditure for the creation of non-UV photons in argon gas at this pressure is measured to be below 378 eV
研究了对氩气、氪气和氙气发出的真空紫外光进行有效收集和检测的可能性。在这些波长处推导了大面积雪崩光电二极管(LAAPDs)的绝对量子效率。用量子效率高于42%的硅雪崩光电二极管，可以探测到波长低至128 nm的Ar发射的VUV光。经测量，在氩发射波长处，涂覆Al+MgF2的柔性聚酯薄膜具有约91%的镜面反射率。低压氩气显示出大量的非紫外线辐射。在此压力下，氩气中产生非紫外光子的平均能量消耗被测量为低于378 eV
{"title":"High efficiency detection of argon scintillation light of 128 nm using LAAPDs","authors":"R. Chandrasekharan, A. Knecht, M. Messina, C. Regenfus, A. Rubbia","doi":"10.1109/NSSMIC.2005.1596232","DOIUrl":"https://doi.org/10.1109/NSSMIC.2005.1596232","url":null,"abstract":"The possibility of efficient collection and detection of vacuum ultraviolet light as emitted by argon, krypton, and xenon gas is studied. Absolute quantum efficiencies of large area avalanche photodiodes (LAAPDs) are derived at these wavelengths. VUV light of wavelengths down to the 128 nm of Ar emission is shown to be detectable with silicon avalanche photodiodes at quantum efficiencies above 42%. Flexible Mylar foil overcoated with Al+MgF2 is measured to have a specular reflectivity of ~91% at argon emission wavelength. Low-pressure argon gas is shown to emit significant amounts of non-UV radiation. The average energy expenditure for the creation of non-UV photons in argon gas at this pressure is measured to be below 378 eV","PeriodicalId":105619,"journal":{"name":"IEEE Nuclear Science Symposium Conference Record, 2005","volume":"65 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127749877","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-11-10DOI: 10.1109/NSSMIC.2005.1596266
R. Wurtz, K. Ziock, L. Fabris, R. Graham
To reach maximum sensitivity, any method used to search for orphan sources must be insensitive to local variations of the background. Using imaging and non-imaging techniques, we analyzed the same data acquired by a large-area, coded-mask-imager search instrument. Data from many passes past a 1 mCi source at 65 m from the instrument were used to construct a model of the instrument response. We then used the model to "hide" the source in data taken in a light urban environment. We compared the success of detecting the hidden sources using coded-mask imaging methods, pseudo-imaging based on a zero-area matched filter, and non-imaging using simple thresholding. The results clearly indicate the superiority of imaging with the coded-mask techniques returning the best results
{"title":"Comparing imaging and non-imaging techniques for reducing background clutter and resolving distant point sources","authors":"R. Wurtz, K. Ziock, L. Fabris, R. Graham","doi":"10.1109/NSSMIC.2005.1596266","DOIUrl":"https://doi.org/10.1109/NSSMIC.2005.1596266","url":null,"abstract":"To reach maximum sensitivity, any method used to search for orphan sources must be insensitive to local variations of the background. Using imaging and non-imaging techniques, we analyzed the same data acquired by a large-area, coded-mask-imager search instrument. Data from many passes past a 1 mCi source at 65 m from the instrument were used to construct a model of the instrument response. We then used the model to \"hide\" the source in data taken in a light urban environment. We compared the success of detecting the hidden sources using coded-mask imaging methods, pseudo-imaging based on a zero-area matched filter, and non-imaging using simple thresholding. The results clearly indicate the superiority of imaging with the coded-mask techniques returning the best results","PeriodicalId":105619,"journal":{"name":"IEEE Nuclear Science Symposium Conference Record, 2005","volume":"52 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122948665","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-11-10DOI: 10.1109/NSSMIC.2005.1596196
M. Burks, D. Chivers, C. Cork, M. Cunningham, L. Fabris, D. Gunter, E. Hull, D. Lange, H. Manini, L. Mihailescu, K. Nelson, T. Niedermayr, J. Valentine, K. Vetter, D. Wright
The point spread function (PSF) of a fully-instrumented silicon/germanium Compton telescope has been measured as a function of energy and angle. Overall, the resolution was 3deg to 4deg FWHM over most of the energy range and field of view. The various contributions to the resolution have been quantified. These contributions include the energy and position uncertainty of the detector; source energy; Doppler broadening; and the 1/r broadening characteristic of Compton back-projection. Furthermore, a distortion of the PSF is observed for sources imaged off-axis from the detector. These contributions are discussed and compared to theory and simulations
{"title":"Imaging performance of the Si/Ge hybrid Compton imager","authors":"M. Burks, D. Chivers, C. Cork, M. Cunningham, L. Fabris, D. Gunter, E. Hull, D. Lange, H. Manini, L. Mihailescu, K. Nelson, T. Niedermayr, J. Valentine, K. Vetter, D. Wright","doi":"10.1109/NSSMIC.2005.1596196","DOIUrl":"https://doi.org/10.1109/NSSMIC.2005.1596196","url":null,"abstract":"The point spread function (PSF) of a fully-instrumented silicon/germanium Compton telescope has been measured as a function of energy and angle. Overall, the resolution was 3deg to 4deg FWHM over most of the energy range and field of view. The various contributions to the resolution have been quantified. These contributions include the energy and position uncertainty of the detector; source energy; Doppler broadening; and the 1/r broadening characteristic of Compton back-projection. Furthermore, a distortion of the PSF is observed for sources imaged off-axis from the detector. These contributions are discussed and compared to theory and simulations","PeriodicalId":105619,"journal":{"name":"IEEE Nuclear Science Symposium Conference Record, 2005","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114724263","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-11-10DOI: 10.1109/NSSMIC.2005.1596437
J. Fairfield
The point spread function (PSF) is an important measure of spatial resolution in CCDs for point-like objects, since it can affect use in imaging and spectroscopic applications. We present new data and theoretical developments in the study of lateral charge diffusion in thick, fully-depleted charge-coupled devices (CCDs) developed at Lawrence Berkeley National Laboratory (LBNL). Because they are fully depleted, the LBNL devices have no field-free region, and diffusion can be controlled through the application of an external bias voltage. We give results for a 3512times3512 format, 10.5 mum pixel back-illuminated p-channel CCD developed for the SuperNova/Acceleration Probe (SNAP), a proposed satellite-based experiment designed to study dark energy. The PSF was measured at substrate bias voltages between 3 V and 115 V. At a bias voltage of 115 V, we measure an rms diffusion of 3.7plusmn0.2 mum. Lateral charge diffusion in LBNL CCDs is thus expected to meet the SNAP requirements
{"title":"Improved spatial resolution in thick, fully-depleted CCDs with enhanced red sensitivity","authors":"J. Fairfield","doi":"10.1109/NSSMIC.2005.1596437","DOIUrl":"https://doi.org/10.1109/NSSMIC.2005.1596437","url":null,"abstract":"The point spread function (PSF) is an important measure of spatial resolution in CCDs for point-like objects, since it can affect use in imaging and spectroscopic applications. We present new data and theoretical developments in the study of lateral charge diffusion in thick, fully-depleted charge-coupled devices (CCDs) developed at Lawrence Berkeley National Laboratory (LBNL). Because they are fully depleted, the LBNL devices have no field-free region, and diffusion can be controlled through the application of an external bias voltage. We give results for a 3512times3512 format, 10.5 mum pixel back-illuminated p-channel CCD developed for the SuperNova/Acceleration Probe (SNAP), a proposed satellite-based experiment designed to study dark energy. The PSF was measured at substrate bias voltages between 3 V and 115 V. At a bias voltage of 115 V, we measure an rms diffusion of 3.7plusmn0.2 mum. Lateral charge diffusion in LBNL CCDs is thus expected to meet the SNAP requirements","PeriodicalId":105619,"journal":{"name":"IEEE Nuclear Science Symposium Conference Record, 2005","volume":"37 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124988703","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-11-09DOI: 10.1109/NSSMIC.2005.1596222
W. Raas, B. Blackburn, E. Boyd, J. Hall, G. Kohse, R. Lanza, B. Rusnak, J. Watterson
Fast neutron resonance radiography (NRR) has recently become a focus of investigation as a supplement to conventional X-ray systems as a non-invasive, non-destructive means of detecting explosive material concealed in checked luggage or cargo containers at airports. Using fast (1-6 MeV) neutrons produced by the D(d,n)3He reaction, NRR provides both an imaging capability and the ability to determine the chemical composition of materials in baggage or cargo. Elemental discrimination is achieved by exploiting the resonance features of the neutron cross-section for oxygen, nitrogen, carbon, and hydrogen. Simulations have shown the effectiveness of multiple-element NRR through Monte Carlo transport methods; this work is focused on the development of a prototype system that will incorporate an accelerator-based neutron source and a neutron detection and imaging system to demonstrate the realistic capabilities of NRR in distinguishing the elemental components of concealed objects. Preliminary experiments have exposed significant technical difficulties unapparent in simulations, including the presence of image contamination from gamma ray production, the detection of low-fluence fast neutrons in a gamma field, and the mechanical difficulties inherent in the use of thin foil windows for gas cell confinement. To mitigate these concerns, a new gas target has been developed to simultaneously reduce gamma ray production and increase structural integrity in high flux gas targets. Development of a neutron imaging system and neutron counting based on characteristic neutron pulse shapes have been investigated as a means of improving signal to noise ratios, reducing irradiation times, and increasing the accuracy of elemental determination
{"title":"Neutron resonance radiography for explosives detection: technical challenges","authors":"W. Raas, B. Blackburn, E. Boyd, J. Hall, G. Kohse, R. Lanza, B. Rusnak, J. Watterson","doi":"10.1109/NSSMIC.2005.1596222","DOIUrl":"https://doi.org/10.1109/NSSMIC.2005.1596222","url":null,"abstract":"Fast neutron resonance radiography (NRR) has recently become a focus of investigation as a supplement to conventional X-ray systems as a non-invasive, non-destructive means of detecting explosive material concealed in checked luggage or cargo containers at airports. Using fast (1-6 MeV) neutrons produced by the D(d,n)3He reaction, NRR provides both an imaging capability and the ability to determine the chemical composition of materials in baggage or cargo. Elemental discrimination is achieved by exploiting the resonance features of the neutron cross-section for oxygen, nitrogen, carbon, and hydrogen. Simulations have shown the effectiveness of multiple-element NRR through Monte Carlo transport methods; this work is focused on the development of a prototype system that will incorporate an accelerator-based neutron source and a neutron detection and imaging system to demonstrate the realistic capabilities of NRR in distinguishing the elemental components of concealed objects. Preliminary experiments have exposed significant technical difficulties unapparent in simulations, including the presence of image contamination from gamma ray production, the detection of low-fluence fast neutrons in a gamma field, and the mechanical difficulties inherent in the use of thin foil windows for gas cell confinement. To mitigate these concerns, a new gas target has been developed to simultaneously reduce gamma ray production and increase structural integrity in high flux gas targets. Development of a neutron imaging system and neutron counting based on characteristic neutron pulse shapes have been investigated as a means of improving signal to noise ratios, reducing irradiation times, and increasing the accuracy of elemental determination","PeriodicalId":105619,"journal":{"name":"IEEE Nuclear Science Symposium Conference Record, 2005","volume":"34 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123059953","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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