Comparative studies of the sensitivities of sparse and full geometries of Total-Body PET scanners built from crystals and plastic scintillators
M. Dadgar*, S. Parzych, J. Baran, N. Chug, C. Curceanu, E. Czerwiński, K. Dulski, K. Elyan, A. Gajos, B.C. Hiesmayr, Ł. Kapłon, K. Klimaszewski, P. Konieczka, G. Korcyl, T. Kozik, W. Krzemień, D. Kumar, S. Niedźwiecki, D. Panek, E. Perez del Rio, L. Raczyński, S. Sharma, Shivani, R.Y. Shopa, M. Skurzok, E. L. Stępień, F. Tayefi Ardebili, K. Tayefi Ardebili, S. Vandenberghe, W. Wiślicki and P. Moskal
abstract
Background: Alongside the benefits of Total-Body imaging modalities, such as higher sensitivity, single-bed position, low dose imaging, etc., their final construction cost prevents worldwide utilization. The main aim of this study is to present a simulation-based comparison of the sensitivities of existing and currently developed tomographs to introduce a cost-efficient solution for
constructing a Total-Body PET scanner based on plastic scintillators.
Methods: For the case of this study, eight tomographs based on the uEXPLORER configuration with different scintillator materials (BGO, LYSO), axial field-of-view (97.4 cm and 194.8 cm), and detector configuration (full and sparse) were simulated. In addition, 8 J-PET scanners with different configurations, such as various axial field-of-view (200 cm and 250 cm), the different cross-sections of plastic scintillator, and the multiple numbers of the
plastic scintillator layers (2, 3, and 4), based on J-PET technology have been simulated by GATE software. Furthermore, Biograph Vision has been simulated to compare the results with standard PET scans. Two types of simulations have been performed. The first one with a centrally located source with a diameter of 1mm and a length of 250 cm, and the second one with the same source inside a water-filled cylindrical phantom with a diameter of 20 cm and a length of 183 cm.
Results: With regards to sensitivity, among all the proposed scanners, the ones constructed with BGO crystals give the best performance (? 350 cps/kBq at the center). The utilization of sparse geometry or LYSO crystals significantly lowers the achievable sensitivity of such systems. The J-PET design gives a similar sensitivity to the sparse LYSO crystal-based detectors while having full detector coverage over the body. Moreover, it provides uniform sensitivity over the body
with additional gain on its sides and provides the possibility for high-quality brain
imaging.
Conclusion: Taking into account not only the sensitivity but also the price of the Total-Body PET tomographs, which till now was one of the main obstacles in their widespread clinical availability, the J-PET tomography system based on plastic scintillators could be a cost-efficient alternative for Total-Body PET scanners.
Efficiency determination of J-PET: first plastic scintillators-based PET scanner
S. Sharma, J. Baran, N. Chug, C. Curceanu, E. Czerwiński, M. Dadgar, K. Dulski, K. Eliyan, A. Gajos, N. Gupta?Sharma, B. C. Hiesmayr, K. Kacprzak, Ł. Kapłon, K. Klimaszewski, P. Konieczka, G. Korcyl, T. Kozik, W. Krzemień, D. Kumar, Sz. Niedźwiecki, D. Panek, S. Parzych, E. Perez del Rio, L. Raczyński, Shivani, R. Y. Shopa, M. Skurzok, E. Ł. Stępień, F. Tayefi, K. Tayefi , W. Wiślicki and P. Moskal
abstract
Background:
The Jagiellonian Positron Emission Tomograph is the 3?layer prototype
of the first scanner based on plastic scintillators, consisting of 192 half?metre?long strips
with readouts at both ends. Compared to crystal?based detectors, plastic scintillators
are several times cheaper and could be considered as a more economical alternative to
crystal scintillators in future PETs. JPET is also a first multi?photon PET prototype. For the
development of multi?photon detection, with photon characterized by the continu?
ous energy spectrum, it is important to estimate the efficiency of J?PET as a function
of energy deposition. The aim of this work is to determine the registration efficiency
of the J?PET tomograph as a function of energy deposition by incident photons and
the intrinsic efficiency of the J?PET scanner in detecting photons of different incident
energies. In this study, 3?hit events are investigated, where 2?hits are caused by 511 keV
photons emitted in e+e? annihilations, while the third hit is caused by one of the
scattered photons. The scattered photon is used to accurately measure the scattering
angle and thus the energy deposition. Two hits by a primary and a scattered photon
are sufficient to calculate the scattering angle of a photon, while the third hit ensures
the precise labeling of the 511 keV photons.
Results:
By comparing experimental and simulated energy distribution spectra, the
registration efficiency of the J?PET scanner was determined in the energy deposition
range of 70?270 keV, where it varies between 20 and 100%. In addition, the intrinsic
efficiency of the J?PET was also determined as a function of the energy of the incident
photons.
Conclusion:
A method for determining registration efficiency as a function of energy
deposition and intrinsic efficiency as a function of incident photon energy of the J?PET
scanner was demonstrated. This study is crucial for evaluating the performance of the
scanner based on plastic scintillators and its applications as a standard and multi?pho?
ton PET systems. The method may be also used in the calibration of Compton?cameras
developed for the ion?beam therapy monitoring and simultaneous multi?radionuclide
imaging in nuclear medicine.
Comparative studies of plastic scintillator strips with high technical attenuation length for the total-body J-PET scanner
Ł. Kapłon, J. Baran, N. Chug, A. Coussat, C. Curceanu, E. Czerwiński, M. Dadgar, K. Dulski, J. Gajewski, A. Gajos, B. Hiesmayr, E. Kavya Valsan, K. Klimaszewski, G. Korcyl, T. Kozik, W. Krzemień, D. Kumar, G. Moskal, S. Niedźwiecki, D. Panek, S. Parzych, E. Pérez del Rio, L. Raczyński, A. Ruciński, S. Sharma, S. Shivani, R. Shopa, M. Silarski, M. Skurzok, E. Stępień, F. Tayefi Ardebili, K. Tayefi Ardebili, W. Wiślicki, P. Moskal
abstract
Plastic scintillator strips are considered as one of the promising solutions for the cost-effective construction of total-body positron emission tomography, (PET) system. The purpose of the performed measurements is to compare the transparency of long plastic scintillators with dimensions 6 mm
24 mm
1000 mm and with all surfaces polished. Six different types of commercial, general purpose, blue-emitting plastic scintillators with low attenuation of visible light were tested, namely: polyvinyl toluene-based BC-408, EJ-200, RP-408, and polystyrene-based Epic, SP32 and UPS-923A. For determination of the best type of plastic scintillator for total-body Jagiellonian positron emission tomograph (TB-J-PET) construction, emission and transmission spectra, and technical attenuation length (TAL) of blue light-emitting by the scintillators were measured and compared. The TAL values were determined with the use of UV lamp as excitation source, and photodiode as light detector. Emission spectra of investigated scintillators have maxima in the range from 420 nm to 429 nm. The BC-408 and EJ-200 have the highest transmittance values of about 90% at the maximum emission wavelength measured through a 6 mm thick scintillator strip and the highest technical attenuation length reaching about 2000 mm, allowing assembly of long detection modules for time-of-flight (TOF) J-PET scanners. Influence of the 6 mm × 6 mm, 12 mm × 6 mm, 24 mm × 6 mm cross-sections of the 1000 mm long EJ-200 plastic scintillator on the TAL and signal intensity was measured. The highest TAL value was determined for samples with 24 mm × 6 mm cross-section.
J-PET detection modules based on plastic scintillators for performing studies with positron and positronium beams
S. Sharma, J. Baran, R.S. Brusa, R. Caravita, N. Chug, A. Coussat, C. Curceanu, E. Czerwinski, M. Dadgar, K. Dulski, K. Eliyan, A. Gajos, B.C. Hiesmayr, K. Kacprzak, L. Kaplon, K. Klimaszewski, P. Konieczka, G. Korcyl, T. Kozik, W. Krzemien D. Kumar, S. Mariazzi, S. Niedźwiecki, L. Panasa, S. Parzych, L. Povolo, E. Perez del Rio, L. Raczynski Shivani, R.Y. Shopa, M. Skurzok, E.L. Stepien, F. Tayefi, K. Tayefi, W. Wislicki and P. Moskal
abstract
The J-PET detector, which consists of inexpensive plastic scintillators, has demonstrated its potential in the study of fundamental physics. In recent years, a prototype with 192 plastic scintillators arranged in 3 layers has been optimized for the study of positronium decays. This allows performing precision tests of discrete symmetries (C, P, T) in the decays of positronium atoms. Moreover, thanks to the possibility of measuring the polarization direction of the photon based on Compton scattering, the predicted entanglement between the linear polarization of annihilation photons in positronium decays can also be studied. Recently, a new J-PET prototype was commissioned, based on a modular design of detection units. Each module consists of 13 plastic scintillators and can be used as a stand-alone, compact and portable detection unit. In this paper, the main features of the J-PET detector, the modular prototype and their applications for possible studies with positron and positronium beams are discussed. Preliminary results of the first test experiment performed on two detection units in the continuous positron beam recently developed at the Antimatter Laboratory (AML) of Trento are also reported.
TOF MLEM Adaptation for the Total-Body J-PET with a Realistic Analytical System Response Matrix
R.Y. Shopa, J. Baran, K. Klimaszewski, W. Krzemień, L. Raczyński, W. Wiślicki, K. Brzeziński, N. Chug, A. Coussat, C. Curceanu, E. Czerwiński, M. Dadgar, K. Dulski, J. Gajewski, A. Gajos, B.C. Hiesmayr, E. Kavya Valsan, G. Korcyl, T. Kozik, D. Kumar, Ł. Kapłon, G. Moskal, S. Niedźwiecki, D. Panek, S. Parzych, E. Pérez del Rio, A. Ruciński, S. Sharma, Shivani, M. Silarski, M. Skurzok, E. Stepień, F. Tayefi Ardebili, K. Tayefi Ardebili, P. Moskal
abstract
We report a study of the original image reconstruction algorithm based on the time-of-flight maximum likelihood expectation maximisation (TOF MLEM), developed for the total-body (TB) Jagiellonian PET (J-PET) scanners. The method is applicable to generic cylindrical or modular multi-layer layouts and is extendable to multi-photon imaging. The system response matrix (SRM) is represented as a set of analytical functions, uniquely defined for each pair of plastic scintillator strips used for the detection. A realistic resolution model (RM) in detector space is derived from fitting the Monte Carlo simulated emissions and detections of annihilation photons on oblique transverse planes. Additional kernels embedded in SRM account for TOF, parallax effect and axial smearing. The algorithm was tested on datasets, simulated in GATE for the NEMA IEC and static XCAT phantoms inside a 24-module 2-layer TB J-PET. Compared to the reference TOF MLEM with none or a shift-invariant RM, an improvement was observed, as evaluated by the analysis of image quality, difference images and ground truth metrics. We also reconstructed the data with additive contributions, pre-filtered geometrically and with non-TOF scatter correction applied. Despite some deterioration, the obtained results still capitalise on the realistic RM with better edge preservation and superior ground truth metrics. The envisioned prospects of the TOF MLEM with analytical SRM include its application in multi-photon imaging and further upgrade to account for the non-collinearity, positron range and other factors.
Realistic Total-Body J-PET Geometry Optimization--Monte Carlo Study
J. Baran, W. Krzemień, L. Raczyński, M. Bała, A. Coussat, S. Parzych, N. Chug, E. Czerwiński, C. Oana Curceanu, M. Dadgar, K. Dulski, K. Eliyan, J. Gajewski, A. Gajos, B. Hiesmayr, K. Kacprzak, Ł. Kapłon, K. Klimaszewski, G. Korcyl, T. Kozik, D. Kumar, S. Niedźwiecki, D. Panek, E. Perez del Rio, A. Ruciński, S. Sharma, Shivani, R.Y. Shopa, M. Skurzok, E. Stępień, F. Tayefiardebili, K. Tayefiardebili, W. Wiślicki, P. Moskal
abstract
Investigation of novel preclinical Total Body PET designed with J-PET technology: A simulation study
M. Dadgar, S. Parzych, F. Tayefi Ardebili, J. Baran, N. Chug, C. Curceanu, E. Czerwiński, K. Dulski, K. Eliyan, A. Gajos, B.C. Hiesmayr, K. Kacprzak, K. Klimaszewski, P. Konieczka, G. Korcyl, T. Kozik, W. Krzemień, D. Kumar, S. Niedźwiecki, D. Panek, E. Perez del Rio, L. Raczyński, S. Sharma, R.Y. Shopa, M. Skurzok, K. Tayefi Ardebili, S. Vandenberghe, W. Wiślicki, E.Ł. Stępień, P. Moskal
abstract
The growing interest in human-grade Total Body PET systems has also application in small animal research. Due to the existing limitations in human-based studies involving drug development and novel treatment monitoring, animalbased research became a necessary step for testing and protocol preparation. In this simulation-based study two unconventional, cost effective small animal Total Body PET scanners (for mouse and rat studies) have been investigated in order to inspect their feasibility for preclinical research. They were designed with the novel technology explored by the Jagiellonian PET Collaboration (J-PET). Two main PET characteristics: sensitivity and spatial resolution were mainly inspected to evaluate their performance. Moreover, the impact of the scintillator dimension and time-offlight on the latter parameter were examined in order to design the most efficient tomographs. The presented results show that for mouse TB J-PET the achievable system sensitivity is equal to 2.35% and volumetric spatial resolution to 9.46 +- 0.54 mm3, while for rat TB J-PET they are equal to 2.6% and 14.11 ? 0.80 mm3, respectively. Furthermore, it was shown that the designed tomographs are almost parallax-free systems, hence they resolve the problem of the acceptance criterion trade-off between enhancing spatial resolution and reducing sensitivity.
ProTheRaMon - a GATE simulation framework for proton therapy range monitoring using PET imaging
D. Borys, J. Baran, K.W. Brzezinski, J. Gajewski, N. Chug, A. Coussat, E. Czerwiński, M. Dadgar, K. Dulski, K. Valsan Eliyan, A. Gajos, K. Kacprzak, Ł. Kapłon, K. Klimaszewski, P. Konieczka, R. Kopec, G. Korcyl, T. Kozik, W. Krzemień, D. Kumar, A. John Lomax, K. McNamara, S. Niedźwiecki, P. Olko, D. Panek, S. Parzych, E. Pérez del Río, L. Raczyński, S. Sharma, S. Shivani, R.Y. Shopa, T. Skóra, M. Skurzok, P. Stasica, E. Stępień, K. Tayefi Ardebili, F. Tayefi, D. Charles Weber, C. Winterhalter, W. Wiślicki, P. Moskal, A. Rucinski
abstract
Objective: This paper reports on the implementation and shows examples of the use of the ProTheRaMon framework for simulating the delivery of proton therapy treatment plans and range monitoring using positron emission tomography (PET). ProTheRaMon offers complete processing of proton therapy treatment plans, patient CT geometries, and intra-treatment PET imaging, taking into account therapy and imaging coordinate systems and activity decay during the PET imaging protocol specific to a given proton therapy facility. We present the ProTheRaMon framework and illustrate its potential use case and data processing steps for a patient treated at the Cyclotron Centre Bronowice (CCB) proton therapy center in Krakow, Poland. Approach: The ProTheRaMon framework is based on GATE Monte Carlo software, the CASToR reconstruction package and in-house developed Python and bash scripts. The framework consists of five separated simulation and data processing steps, that can be further optimized according to the user's needs and specific settings of a given proton therapy facility and PET scanner design. Main results: ProTheRaMon is presented using example data from a patient treated at CCB and the J-PET scanner to demonstrate the application of the framework for proton therapy range monitoring. The output of each simulation and data processing stage is described and visualized. Significance: We demonstrate that the ProTheRaMon simulation platform is a high-performance tool, capable of running on a computational cluster and suitable for multi-parameter studies, with databases consisting of large number of patients, as well as different PET scanner geometries and settings for range monitoring in a clinical environment. Due to its modular structure, the ProTheRaMon framework can be adjusted for different proton therapy centers and/or different PET detector geometries. It is available to the community via github.
Development of the Normalization Method for the Jagiellonian PET Scanner
A. Coussat, W. Krzemien, J. Baran, S. Parzych
abstract
This work aims at applying the theory of the component-based normalization to the Jagiellonian PET
scanner, currently under development at the Jagiellonian University. In any positron emission tomography acquisition, efficiency along a line-of-response can vary due to several physical and geometrical
effects, leading to severe artifacts in the reconstructed image. To mitigate these effects, a normalization
coefficient is applied to each line-of-response, defined as the product of several components. The specificity of the Jagiellonian PET scanner geometry is taken into account. The results obtained from the
GATE simulations are compared with the preliminary results obtained from the experimental data.
Testing CPT symmetry in ortho-positronium decays with positronium annihilation tomography
P. Moskal, A. Gajos, M. Mohammed, J. Chhokar, N. Chug, C. Curceanu, E. Czerwiński, M. Dadgar, K. Dulski, M. Gorgol, J. Goworek, B. Hiesmayr, B. Jasińska, K. Kacprzak, Ł. Kapłon, H. Karimi, D. Kisielewska, K. Klimaszewski, G. Korcyl, P. Kowalski, N. Krawczyk, W. Krzemień, T. Kozik, E. Kubicz, S. Niedźwiecki, S. Parzych, M. Pawlik-Niedźwiecka, L. Raczyński, J. Raj, S. Sharma, S. Choudhary, R. Shopa, A. Sienkiewicz, M. Silarski, M. Skurzok, E. Stepien, F. Tayefi, W. Wiślicki
abstract
Charged lepton system symmetry under combined charge, parity, and time-reversal transformation (CPT) remain scarcely tested. Despite stringent quantum-electrodynamic limits, discrepancies in predictions for the electron-positron bound state (positronium atom) motivate further investigation, including fundamental symmetry tests. While CPT noninvariance effects could be manifested in non-vanishing angular correlations between final-state photons and spin of annihilating positronium, measurements were previously limited by the knowledge of the latter. Here, we demonstrate tomographic reconstruction techniques applied to three-photon annihilations of ortho-positronium atoms to estimate their spin polarisation without a magnetic field or polarised positronium source. We use a plastic-scintillator-based positron-emission-tomography scanner to record ortho-positronium (o-Ps) annihilations with a single-event estimation of o-Ps spin and determine the complete spectrum of an angular correlation operator sensitive to CPT-violating effects. We find no violation at the precision level of 10^{-4}, with an over threefold improvement on the previous measurement.
A Simulation Study to Estimate Optimum LOR Angular Acceptance for the Image Reconstruction with the Total-Body J-PET
M. Dadgar, S. Parzych and F. Tayefi Ardebili
abstract
One of the directions in today's development of PET scanners is to increase their axial field of view (AFOV). Currently limited to several centimeters, AFOV of the clinically available PET tomographs results in a very low sensitivity (~1%) and requires an extended time for a scan of a whole human body. While these drawbacks are addressed in the so-called, Total Body PET concept (scanner with a significantly elongated field of view), it creates new challenges not only in the mechanical construction but also in image reconstruction and event selection. The possibility of taking into account of large-angle variety of lines of responses (LORs) contributes positively to the sensitivity of the tomograph. However, at the same time, the most oblique LORs have an unfavorable influence on the spatial resolution due to the parallax error and large contribution to the scatter fraction. This forces to determine a new factor -acceptance angle - which is a maximum azimuthal angle for which the LORs are still taken into image reconstruction. Correct determination of such factors is imperative to maximize the performance of a Total Body PET system since it introduces a trade-off between the two main characteristics of scanners: sensitivity and spatial resolution.
This work has been dedicated to the estimation of the optimal acceptance angle for the proposed by the Jagiellonian PET (J-PET) Collaboration Total Body tomograph. J-PET Collaboration introduces a novel, cost-effective approach to PET systems development with the use of organic scintillators. This simulation study provides evidence that the 45-degree acceptance angle cut can be an appropriate choice for the investigated scanner.
Design, structure, microstructure and gamma radiation shielding properties of refractory concrete materials containing Ba- and Sr-doped cements
D. Madej , M. Silarski , S. Parzych
abstract
This paper presents an experimental study on the performance of shielding refractory concretes containing new types of cement for use in radiation protection technology. Three concretes with corundum aggregate and special refractory inorganic cements belonging to the CaO-Al2O3, SrO-CaO-Al2O3-ZrO2, SrO-Al2O3 and BaO-CaO-Al2O3-ZrO2 systems were tested. The products formed in the hydration of these binders were detected by SEM-EDS. The linear attenuation coefficients obtained from measurements with ? quanta emitted by the following sources: 22Na, 137Cs, 60Co, 133Ba and 152Eu in the range of 80-1408 keV were determined twice,
firstly after casting and drying (110 oC) of concretes, and secondly after sintering at 1400 oC. Especially, this work fills the gap in the literature providing the gamma rays attenuation properties of cement-containing heat resistant corundum concretes in the energy region between 779 keV and 1112 keV. The experimental setup equipped with the ORTEC GMX25P4-70 High Purity Germanium detector (HPGe) cooled with liquid nitrogen was used for the determination of the gamma-ray linear attenuation coefficients of new materials. The role of the cement on the compressive and bending strengths, pore structure (mercury intrusion porosimetry), phase
composition (XRD, FT-IR), and microstructure (SEM-EDS) of heat-treated concretes was reported. It was found that the incorporation of Sr or Ba and Zr elements with cements improved the attenuation properties of corundum-based concretes, in comparison to the concretes containing Ca. The doping alkaline earth elements i.e. Sr and Ba were chemically bonded within both hydraulic matrix of green concretes and ceramic matrix formed in concrete through sintering at 1400 ?C. Hence, these materials with gamma radiation shielding capacity are designed for special construction applications.
Upper limit on the eta->pi+pi- branching fraction with the KLOE experiment
D. Babusci, M. Berlowski, C. Bloise, F. Bossi, P. Branchini, A. Budano, B. Cao, F. Ceradini, P. Ciambrone, F. Curciarello, E. Czerwiński, G. D'Agostini, E. Dan?, V. De Leo, E. De Lucia, A. De Santis, P. De Simone, A. Di Cicco, A. Di Domenico, D. Domenici, A. D'Uffizi, A. Fantini, P. Fermani, S. Fiore, A. Gajos, P. Gauzzi, S. Giovannella, E. Graziani, V. L. Ivanov, T. Johansson, X. Kang, D. Kisielewska-Kamińska, E. A. Kozyrev, W. Krzemien, A. Kupsc, P. A. Lukin, G. Mandaglio, M. Martini, R. Messi, S. Miscetti, D. Moricciani, P. Moskal, S. Parzych, A. Passeri, V. Patera, E. Perez del Rio, P. Santangelo, M. Schioppa, A. Selce, M. Silarski, F. Sirghi, E. P. Solodov, L. Tortora, G. Venanzoni, W. Wiślicki, M. Wolke
abstract
Based on an integrated luminosity of 1.61 fb^{-1} e+e- collision data collected with the KLOE detector at DAFNE, the Frascati phi-factory, a search for the P- and CP-violating decay eta->pi+pi- has been performed. Radiative phi->eta gamma decay is exploited to access the eta mesons. No signal is observed in the pi+pi- invariant mass spectrum, and the upper limit on the branching fraction at 90% confidence level is determined to be B(eta->pi+pi-)<4.9x10^{-6}, which is approximately three times smaller than the previous KLOE result. From the combination of these two measurements we get B(eta->pi+pi-)<4.4x10^{-6} at 90% confidence level.
Measurement of the branching fraction for the decay KS -> pi mu nu with the KLOE detector
D. Babusci, M. Berlowski, C. Bloise, F. Bossi, P. Branchini, A. Budano, B. Cao, F. Ceradini, P. Ciambrone, F. Curciarello, E. Czerwisnski, G. D'Agostini, E. Dane, V. De Leo, E. De Lucia, A. De Santis, P. De Simone, A. Di Cicco, A. Di Domenico, D. Domenici, A. D'Uffizi, A. Fantini, P. Fermani, S. Fiore, A. Gajos, P. Gauzzi, S. Giovannella, E. Graziani, V. L. Ivanov, T. Johansson, X. Kang, D. Kisielewska-Kamisnska, E. A. Kozyrev, W. Krzemien, A. Kupsc, P. A. Lukin, G. Mandaglio, M. Martini, R. Messi, S. Miscetti, D. Moricciani, P. Moskal, S. Parzych, A. Passeri, V. Patera, E. Perez del Rio, P. Santangelo, M. Schioppa, A. Selce, M. Silarski, F. Sirghi, E. P. Solodov, L. Tortora, G. Venanzoni, W. Wislicki, M. Wolke
abstract
Based on a sample of 300 million KS mesons produced in phi -> KLKS decays recorded by the KLOE experiment at the DAFNE e+e- collider we have measured the branching fraction for the decay KS -> pi mu nu. The KS mesons are identified by the interaction of KL mesons in the detector. The KS -> pi mu nu decays are selected by a boosted decision tree built with kinematic variables and by a time-of-flight measurement. Signal efficiencies are evaluated with data control samples of KL -> pi mu nu decays. A fit to the reconstructed muon mass distribution finds 7223?180 signal events. Normalising to the KS -> pi+ pi- decay events the result for the branching fraction is B(KS -> pi mu nu) = (4.56+-0.11stat+-0.17syst)×10-4.
Application of multivariate analysis in search of the Ks->3pi0 decay in the KLOE experiment
S. Parzych
abstract
According to the Standard Model, one of the purely CP-violating processes is the never observed KS->3pi0 decay. The best upper limit on the branching ratio of this process BR(KS->3p0)<2.6×10^-8 was obtained in the KLOE experiment using cut-based analysis. In this paper, we show preliminary results of an alternative approach to those studies using multivariate analysis methods.
