56308013
Supplemental Proposal to the ALCPG and LCDRD Groups for the Comprehensive Study, Construction and Testing of Multiple Readout Calorimeters of the 4th Concept
We propose a comprehensive assault on the main problems of high-precision hadronic calorimetry for physics at the International Linear Collider (ILC), including (i) the design, construction and testing of a cubic-meter dual-fiber readout module to suppress the leakage fluctuations that limited the performance of the I-tonne DREAM modulel ; (ii) measurement of the MeV-neutron content of hadronic showers to suppress binding energy fluctuations in hadronic shower development; (iii) further testing of a dual-readout crystal front-end to the fiber calorimeter to achieve better e± and 'Y measurements; (iv) design of a photo converter to replace the PMTs used in the DREAM beam tests, (v) additions to the GEANT 4 package to improve the simulation of the main features of hadronic calorimetry, in particular, the known and well-measured EM fraction compensation mechanisms, neutron compensation mechanisms, electromagnetic content measurements, and the differences between pion and proton showers in highly non-compensating calorimeters; and, (vi) a slice test of the 4th concept design with a muon system behind the cubic-meter module and a TPC prototype in front. The goal is a complete test of the calorimeter principles and a demonstration of the particle identification probabilities and the spatial and energy a resolution capabilities of a "full" 4th concept detector. This proposal directly addresses the highest priority issue of the 4th concept: the energy and spatial resolutions of hadronic showers in a dual-readout calorimeter with a geometry that can be scaled to a full ILC detector and with a TPC in a magnetic field. This work follows directly from our previous beam tests of the small I-tonne prototype DREAM module. In a series of papers describing a wide variety of dual-readout calorimetric measurements of hadrons and jets [1], electrons [3], muons [4], the different spatial distributions of Cerenkov and scintillation light in showers [5], and the separability of Cerenkov and scintillation light in a single optical medium [6], we have shown, in this small module calibrated with 40 GeV electrons, that the electromagnetic response is linear from 20 to 200 GeV, hadronic response is linear from 30 to 300 GeV, the energy response is Gaussian, and the energy resolution is improved OVer the case of a pure scintillating calorimeter. The main goal, or milestone, is a module that is sufficiently massive that leakage fluctuations are not a concern for energy resolution, and a module that achieves an energy resolution of O"E 20% If::::: ..[E' or better, for incident pions or interaction jets. This test cannot be made with less funding and this goal represents a critical and central milestone for the 4th concept. No other concept group is working on dual and multiple readout calorimetry, and we welcome both participants and observers. This proposal, in essence, was submitted to the Damerell committee 2 some months ago, and the calorimeter module costs remain unchanged. Since this is our only need, it is proposed here with the additions of software and simulation work, dedicated electronics, and the extra costs of a slice test. IThe DREAM module was never intended to achieve high-precision and was limited to I-tonne of Cu by funding constraints, but it did achieve its goal of demonstrating that a dual readout calorimeter is easily feasible and offers several substantial benefits for experimental calorimetry. 2This was an informal request to the concept groups for their critical R&D needs. Collaborators are all 4th Concept participants and other interested members of the ILC detector community, especially TPC and pixel vertex detector proponents, for a "slice test" of multiple and sequential ILC detectors in a beam. The dual-readout calorimetry The main idea of multiple readout calorimetry is to independently measure those physical quantities that fluctuate in a hadronic shower and that lead to fluctuations in energy response, and sum over those physical quantities that do not lead to fluctuations in energy response. Thus, the huge fluctuations in electromagnetic energy fraction, f em, are directly measured with Cerenkov light generated in clear plastic fibers primarily by the very relativistic electrons in the shower, the transverse spatial fluctuations are sampled on the millimeter scale with high spatial density optical fibers, the fluctuations in binding energy losses will be measured by the MeV neutrons in the volume, whereas the longitudinal depth development fluctuations are summed in depth. This last statement may, at first, seem counter-intuitive, but it is a great strength: hadronic showers with widely differing depth deposition fluctuations have the same total light output independent of their depth development [9]. The calorimetric measurement of hadronic particle energies has been bedeviled for decades by 1. poor energy resolution, typically 80 -120%IVE for big detectors. There are a few exceptions, such as ZEUS at DESY, with elk:::::: 1, which consequently fixed the senser-absorber ratio at a low value; 2. non-Gaussian response. Usually, a high-side tail3 is a characteristic of hadron calorimeters; 3. non-linearity with energy. The calorimeter response is not linear with incident particle energy. These serious deficiencies are generally understood to be due to several factors: a nonequal response to electromagnetic and hadronic shower energy deposits ("elk ¥= I"), the fall-off of calorimeter response to lower energy hadrons in the few-GeV region, the huge fluctuations in electromagnetic energy fraction from shower-to-shower, the degrees of absorption of neutrons, the integration time of the signal especially in regard to the slower neutron signal, and variation of the mean electromagnetic shower fraction with increasing hadron energy. These phenomena affect the above list of problems in different ways. This dual-readout calorimeter has the following main features, as can be seen in the paper on hadronic energy measurement [1]: 1. the energy resolution is expected to be excellent, about 20 25%jVE for 1I"'S and "jets" in a module with negligible leakage fluctuations; 2. the response is Gaussian, to a good approximation; and, 3. the response is linear in hadronic beam energy in a calorimeter that was calibmted only with 40 Ge V electrons. 3It is clear that a high-side calorimeter energy tail can generate fake high-mass objects and must be avoided. Of these three beneficial features, the third is probably the most important. At the ILC, a detector will be calibrated at the ZO, i.e., 45 GeV e±, J.t± and jets, and will be expected to measure with high precision the energies of particles and jets up to 500 GeV. This factor of 10 extrapolation will require a lot of faith, because there will be no test beam.4 However, in the 4th concept detector, this capablility is intrinsic to the calorimeter itself. The device is explicitly linear on the mm spatial scale, and the direct simultaneous measurements of electromagnetic and hadronic energies are coupled so that a calibration with electrons results in linear hadronic energy response. Dual readout crystal front section The DREAM module was exposed to an electron beam from 20 to 200 GeV and, since the scintillating and Cerenkov fibers are both equally sensitive to electromagnetic showers, the response functions are essentially the same. However, the Cerenkov resolution is limited by the finite photoelectron (pe) statistics of rv 18pe/GeV, whereas the scintillation luminosity was a factor of 20 higher, but still limited to 20.5%/.,(E + 1.5%. We have begun the testing of PbW04 crystals for dual-readout of scintillation and Cerenkov light [10) to achieve greatly enhanced pe yield and therefore better EM energy resolution. The smaller channel size will yield better spatial resolution on electrons and photons. The dual-readout will allow these advantages without losing hadronic energy resolution.s Preliminary results from our LCRD proposal [7] were presented at the Elba conference [10) and parts were presented at CALOR06 [11). Proposed work We propose to test additions and improvements over the present tested proof-of-principle DREAM module, viz., 1. a dual-readout crystal front section with excellent transverse segmentation and excellent electromagnetic energy and spatial resolutions; 2. each fiber will be inserted into its own groove; this will increase the statistical resolution over the DREAM module by reducing the correlation in multiple fiber signals (both scintillating and Cerenkov ) arising from the passage of a single track; 3. construct the absorber matrix of bras..<). 4. readout both the scintillating fibers and the Cerenkov fibers in time, out to about 300 ns, to catch the slow neutrons whose energy is roughly proportional to the binding energy (BE) losses in nuclei in hadronic showers. These neutrons are approximately T rv 1 MeV, and their velocity is v :::::: ..j2T/Mn :::::: 0.05c. For a mean neutron interaction length of several centimeters, the expanding neutron 4 All calorimeters in most experiments at high energies have this problem, and specifically the HF calorimeters on CMS must measure 3 TeV jets having been calibrated only on 0.3 TeV pions. There is a scheme to pitch the 7 TeV proton beam with a bent crystal into HF to calibrate. This would be harder to do at the ILC. A good problem to solve would be the design of a halo proton scraper during LHC running to achieve a parasitic low flux TeV-scale beam. 5Roughly, half of all hadrons interaction in the "EM" section, which must therefore also be a "hadronic" section. content produced by a showering jet will fill possibly 0.5 m3 over a few hundred
118168382
First observation of the isospin violating decay $J/\psi\rightarrow \Lambda\bar{\Sigma}^{0}+c.c.$
Using a sample of $(225.2\pm 2.8)\times 10^6$ $J/\psi$ events collected with the BESIII detector, we present results of a study of $J/\psi\rightarrow \gamma\Lambda\bar{\Lambda}$ and report the first observation of the isospin violating decay $J/\psi\rightarrow\Lambda\bar{\Sigma}^{0}+c.c.$, in which $\bar{\Sigma}^{0}$ decays to $\gamma \bar{\Lambda}$. The measured branching fractions are $\mathcal{B}(J/\psi\rightarrow\bar{\Lambda}\Sigma^{0}$) = $(1.46\pm0.11\pm0.12) \times10^{-5}$ and $\mathcal{B}(J/\psi\rightarrow\Lambda\bar{\Sigma^{0}}$) = $(1.37\pm0.12\pm0.11) \times10^{-5}$. We search for $\Lambda(1520) \rightarrow \gamma \Lambda$ decay, and find no evident signal, and an upper limit for the product branching fraction $\mathcal{B}(J/\psi\rightarrow\Lambda\bar{\Lambda}(1520)+c.c.)\times \mathcal{B}(\Lambda(1520)\rightarrow\gamma\Lambda)<4.1 \times10^{-6}$ is set at the 90% confidence level. We also report the observation of $\eta_{c}\rightarrow\Lambda\bar{\Lambda}$ in $J/\psi \rightarrow \gamma \eta_{c}$, $\eta_{c}\rightarrow\Lambda\bar{\Lambda}$ and measure the branching fraction $\mathcal{B}(\eta_{c}\rightarrow\Lambda\bar{\Lambda}) =(1.16\pm0.12 (stat)\pm0.19(syst)\pm0.28(PDG))\times10^{-3}$.
118348268
Measurement of $y_{CP}$ in $D^0-\overline{D}^0$ oscillation using quantum correlations in $e^+e^-\to D^0\overline{D}^0$ at $\sqrt{s}$ = 3.773\,GeV
We report a measurement of the parameter $y_{CP}$ in $\ensuremath{D^0}\xspace-\ensuremath{\overline{D}^{0}}\xspace$ oscillations performed by taking advantage of quantum coherence between pairs of $\ensuremath{D^0}\xspace \ensuremath{\overline{D}^{0}}\xspace$ mesons produced in $e^+e^-$ annihilations near threshold. In this work, doubly-tagged $\ensuremath{D^0}\xspace \ensuremath{\overline{D}^{0}}\xspace$ events, where one $D$ decays to a $CP$ eigenstate and the other $D$ decays in a semileptonic mode, are reconstructed using a data sample of 2.92\,fb$^{-1}$ collected with the BESIII detector at the center-of-mass energy of $\sqrt{s}$ = 3.773\,GeV. We obtain $y_{CP} = (-2.0\pm1.3\pm0.7)\%$, where the first uncertainty is statistical and the second is systematic. This result is compatible with the current world average.
120279709
Level-0 trigger algorithms for the ALICE PHOS detector
Abstract The PHOS level-0 trigger provides a minimum bias trigger for p–p collisions and information for a level-1 trigger at both p–p and Pb–Pb collisions. There are two level-0 trigger generating algorithms under consideration: the Direct Comparison algorithm and the Weighted Sum algorithm. In order to study trigger algorithms via simulation, a simplified equivalent model is extracted from the trigger electronics to derive the waveform function of the Analog-or signal as input to the trigger algorithms. Simulations shown that the Weighted Sum algorithm can achieve higher trigger efficiency and provide more precise single channel energy information than the direct compare algorithm. An energy resolution of 9.75 MeV can be achieved with the Weighted Sum algorithm at a sampling rate of 40 Msps (mega samples per second) at 1 GeV. The timing performance at a sampling rate of 40 Msps with the Weighted Sum algorithm is better than that at a sampling rate of 20 Msps with both algorithms. The level-0 trigger can be delivered to ALICE CTP within 800 ns with a timing uncertainty of 2 LHC bunch crossing cycles.
119274043
Partial wave analysis of $J/\psi \to \gamma \eta \eta$
Based on a sample of $2.25\times 10^{8}$ $J/\psi$ events collected with the BESIII detector at BEPCII, a full partial wave analysis on $J/\psi\to\gamma\eta\eta$ was performed using the relativistic covariant tensor amplitude method. The results show that the dominant $0^{++}$ and $2^{++}$ components are from the $f_0(1710)$, $f_0(2100)$, $f_0(1500)$, $f_2'(1525)$, $f_2(1810)$ and $f_2(2340)$. The resonance parameters and branching fractions are also presented.
53857242
Study of the near-threshold ωϕ mass enhancement in doubly OZI-suppressed J/ψ→γωϕ decays
A 2:25 x 10(8) J/psi event sample accumulated with the BESIII detector is used to study the doubly Okubo-Zweig-Iizuka-suppressed decay modes J/psi -> gamma omega phi, omega -> pi(+)pi(-)pi(0), phi -> K+K-. A strong deviation (> 30 sigma) from three-body J/psi -> gamma omega phi phase space is observed near the omega phi mass threshold that is consistent with a previous observation reported by the BESII experiment. A partial wave analysis with a tensor covariant amplitude that assumes that the enhancement is due to the presence of a resonance, the X(1810), is performed and confirms that the spin-parity of the X(1810) is 0(++). The mass and width of the X(1810) are determined to be M = 1795 +/- 7(stat)(-5)(+13) (syst) +/- 19(mod) MeV/c(2) and Gamma = 95 +/- 10(stat)(-34)(+21)(syst) +/- 75(mod) MeV/c(2), respectively, and the product branching fraction is measured to be B(J/psi -> gamma X(1810)) x B(X(1810) -> omega phi) = (2.00 +/- 0.08(stat)(-1.00)(+0.45)(syst) +/- 1.30(mod)) x 10(-4). These results are consistent within errors with those of the BESII experiment. DOI: 10.1103/PhysRevD.87.032008
118789309
Measurements of the observed cross sections for e+e- ---> exclusive light hadrons containing pi0 pi0 at s**(1/) = 3.773, 3.650 and 3.6648-GeV
Abstract By analyzing the data sets of 17.3, 6.5 and 1.0 pb−1 taken, respectively, at s = 3.773 , 3.650 and 3.6648 GeV with the BES-II detector at the BEPC collider, we measure the observed cross sections for e + e − → π + π − π 0 π 0 , K + K − π 0 π 0 , 2 ( π + π − π 0 ) , K + K − π + π − π 0 π 0 and 3 ( π + π − ) π 0 π 0 at the three energy points. Based on these cross sections we set the upper limits on the observed cross sections and the branching fractions for ψ ( 3770 ) decay into these final states at 90% C.L.
32357992
Charmonium Decays of Y(4260), psi(4160), and psi(4040).
Using data collected with the CLEO detector operating at the CESR e+e- collider at sqrt[s]=3.97-4.26 GeV, we investigate 15 charmonium decay modes of the psi(4040), psi(4160), and Y(4260) resonances. We confirm, at 11 sigma significance, the BABAR Y(4260)-->pi+pi- J/psi discovery, make the first observation of Y(4260)--> pi(0)pi(0) J/psi (5.1 sigma), and find the first evidence for Y(4260)-->K+K- J/psi(3.7 sigma). We measure e+e- cross sections at sqrt[s]=4.26 GeV as sigma(pi+pi- J/psi)=58(+12)(-10)+/-4 pb, sigma(pi(0)pi(0) J/psi)=23(+12)(-8)+/-1 pb, and sigma(K+K- J/psi)=9(+9)(-5)+/-1 pb, in which the uncertainties are statistical and systematic, respectively. Upper limits are placed on other decay rates from all three resonances.
118416601
Testing a Neutrino Mass Generation Mechanism at the LHC
The Large Hadron Collider could be a discovery machine for the neutrino mass pattern and its Majorana nature in the context of a well-motivated TeV scale Type II seesaw model. This is achieved by identifying the flavor structure of the lepton-number violating decays of the charged Higgs bosons. The observation of either H{sup +}{yields}{tau}{sup +}{nu} or H{sup +}{yields}e{sup +}{nu} will be particularly robust to determine the neutrino spectra since they are independent of the unknown Majorana phases, which could be probed via the H{sup ++}{yields}e{sub i}{sup +}e{sub j}{sup +} decays. In a less favorable scenario when the leptonic channels are suppressed, one needs to observe the decays H{sup +}{yields}W{sup +}H{sub 1} and H{sup +}{yields}tb to confirm the triplet-doublet mixing that implies the Type II relation. The associated production H{sup {+-}}{sup {+-}}H{sup {+-}} is crucial in order to test the triplet nature of the Higgs field.
119640767
Measurement of the final states omega pi0, rho eta, and rho eta prime from psi (2S) electromagnetic decays and e+e- annihilations
Cross sections and form factors for $\ee \to \wpi$, $\rho\eta$, and $\rho\etap$ at center of mass energies of 3.650, 3.686, and 3.773 GeV are measured using data samples collected with the BESII detector at the BEPC. Also, the branching fractions of $\psi(2S) \rar \wpi$, $\rho\eta$, and $\rho\etap$ are determined to be $(1.87^{+0.68}_{-0.62}\pm0.28)\times 10^{-5}$, $(1.78^{+0.67}_{-0.62}\pm0.17)\times 10^{-5}$, and $(1.87^{+1.64}_{-1.11}\pm0.33)\times10^{-5}$, respectively.