Free Proton Research Articles

Effects of in-medium nucleon-nucleon cross sections on stopping observable and ratio of free protons in heavy-ion collisions at 400 MeV/nucleon

The effects of in-medium nucleon-nucleon cross sections on the stopping observable and ratio of free protons in heavy-ion collisions at 400MeV/nucleon have been investigated within the framework of the IQMD+GEMINI model. Five kinds of in-medium corrections of nucleon-nucleon cross sections, which are considerably different in the referred energy and density, have been used in the model. It has been found that calculations of the stopping decrease when the in-medium cross sections decrease. Moreover, the ratio of free protons Rp depends not only on the value of the in-medium factors but also on its isospin dependence. In order to investigate the isospin effect of in-medium factors on the ratio of free protons Rp, the isospin dependence of in-medium factors has been adjusted and used in the model. The calculations have shown that the isospin dependence of in-medium factors does not impact the stopping, but impacts the ratio of free protons Rp. When the in-medium factors relation f nn med > f pp med is used in the model, the calculated values of Rp are larger than those in the f nn med < f pp med case.

Impact of the $$\gamma _{\nu }$$NN* Electrocoupling Parameters at High Photon Virtualities and Preliminary Cross Sections off the Neutron

Meson-photoproduction measurements and their reaction-amplitude analyses can establish more sensitively, and in some cases in an almost model-independent way, nucleon excitations and non-resonant reaction amplitudes. However, to investigate the strong interaction from already explored—where meson-cloud degrees of freedom contribute substantially to the baryon structure—to still unexplored distance scales—where quark degrees of freedom dominate and the transition from dressed to current quarks occurs—we depend on experiments that allow us to measure observables that are probing this evolving non-perturbative QCD regime over its full range. Elastic and transition form factors are uniquely suited to trace this evolution by measuring elastic electron scattering and exclusive single-meson and double-pion electroproduction cross sections off the nucleon. These exclusive measurements will be extended to higher momentum transfers with the energy-upgraded CEBAF beam at JLab to study the quark degrees of freedom, where their strong interaction is responsible for the ground and excited nucleon state formations. After establishing unprecedented high-precision data, the imminent next challenge is a high-quality analysis to extract these relevant electrocoupling parameters for various resonances that can then be compared to state-of-the-art models and QCD-based calculations. The vast majority of the available exclusive electroproduction cross sections are off the proton. Hence flavor-dependent analyses of excited light-quark baryons are lacking experimental data off the neutron. The goal is to close this gap by providing exclusive \({\gamma }_{\nu }(n) \rightarrow p^{+} {\pi }^{-}\) reaction cross section off deuterium and to establish a kinematical final-state-interaction (FSI) correction factor (R) map that can be determined from the data set itself. The “e1e” Jefferson Lab CLAS data set, that is analyzed, includes both a hydrogen and deuterium target run period, which allows a combined analysis of the pion electroproduction off the free proton, the bound proton, and the bound neutron under the same experimental conditions. Hence it will provide the experimentally best possible information on the off-shell and FSI effects in deuterium, which must be considered in order to extract the information off the neutron. The cross section analysis of this data set, that is currently underway, will considerably improve our knowledge of the \(Q^{2}\) evolution of resonance states off bound protons and neutrons. Recent results presented here and in these proceedings are demonstrating the status and continuous progress of data analyses and their theoretical descriptions, as well as highlighting the experimental and theoretical outlook of what shall and may be achieved in the new era of the 12-GeV upgraded transition form factor program.

Induced Potential in Porous Carbon Films through Water Vapor Absorption.

Sustainable electrical potential of tens of millivolts can be induced by water vapor adsorption on a piece of porous carbon film that has two sides with different functional group contents. Integrated experiments, and Monte Carlo and ab initio molecular dynamics simulations reveal that the induced potential originates from the nonhomogeneous distribution of functional groups along the film, especially carboxy groups. Sufficient adsorbed water molecules in porous carbon facilitate the release of protons from the carboxy groups, resulting in a potential drop across the carbon film because of the concentration difference of the released free protons on the two sides. The potential utilization of such a phenomenon is also demonstrated by a self-powered humidity sensor.

Induced Potential in Porous Carbon Films through Water Vapor Absorption

AbstractSustainable electrical potential of tens of millivolts can be induced by water vapor adsorption on a piece of porous carbon film that has two sides with different functional group contents. Integrated experiments, and Monte Carlo and ab initio molecular dynamics simulations reveal that the induced potential originates from the nonhomogeneous distribution of functional groups along the film, especially carboxy groups. Sufficient adsorbed water molecules in porous carbon facilitate the release of protons from the carboxy groups, resulting in a potential drop across the carbon film because of the concentration difference of the released free protons on the two sides. The potential utilization of such a phenomenon is also demonstrated by a self‐powered humidity sensor.

Uric acid bladder stones in congenital cyanotic heart disease

A 54-year-old man was admitted with a 4-year history of recurrent urinary tract infections. He had a history of osteoarthritis of the left hip and benign prostatic enlargement. Physical examination showed clubbing with cyanosis (fi gure), and a grade 4/6 systolic murmur throughout the praecordium. Electrocardiogram showed right ventricular hypertrophy with features of pressure overload (appendix). His haemoglobin was raised at 200 g/L, with a haematocrit of 0·53. A CT scan of the genitourinary system showed multiple large urinary bladder stones (fi gure), urinary bladder wall thickening, trabeculations and diverticulae, and bilateral hydroureters and hydronephrosis. Cardiac MRI showed features consistent with unrepaired tetralogy of Fallot, including a large ventricular septal defect with bidirectional shunting. Cardiac catheterisation showed normal coronary arteries and pulmonary vascular resistance. Ten large bladder stones were removed by open surgery, for symptom relief and to decompress the related obstructive uropathy, measuring up to 3·3 cm in diameter (fi gure). Gas chromatography-mass spectrometry showed that the stones were composed of uric acid. Our patient later had corrective surgery for prognostic and symptomatic improvement of his suprasystemic right ventricular systolic pressure and pulmonary stenosis. Patients with cyanotic heart disease have compensatory erythrocytosis as a physiological response to persistent hypoxia, associated with a shortened red blood cell lifespan. This can cause increased red cell turnover leading to high purine metabolism and uric acid production. The most common factors that promote uric acid stone formations are persistently low urinary pH, dehydration leading to low urinary volume, and high uric acid production. Nitrogen atoms from urate interact with free protons to form uric acid that is 20 times less soluble than urate. Low pH promotes urate conversion to uric acid, which is less soluble and so more prone to forming crystals. At persistently low pH uric acid crystals can form and stabilise even with normal urinary urate concentration. Intermittent alkalinisation of urine dissolves crystals that have formed and promotes urinary stone resorption, although patients with hyperuricosuria do not form uric acid stones in the presence of alkaline urine. The underlying physiology that leads to persistently low urinary pH is poorly understood. Oral agents to modify urinary pH are available, but minimally invasive surgery is the treatment of choice for patients with symptomatic urinary bladder stones. Our patient had slightly raised plasma uric acid, with normal 24-h urinary uric acid and plasma creatinine levels. The electronic patient record had recorded a persistently low urinary pH over the last few years. He now has regular urological follow-up. We suggest that hyperuricaemia combined with persistently low urinary pH, which led to bladder stone formation, was caused by appropriate secondary erythrocytosis, turnover, and breakdown in the setting of cyanotic congenital heart disease.

Spontaneous Photon Emissions in Photoreceptors: Potential Convergence of Arrhenius Reactions and the Latency for Rest Mass Photons to Accelerate to Planck Unit Energies

         Spontaneous or phasic voltage shifts normally occur across the plasma membranes of photoreceptors without impingement from external photons on average once every ~38 s (26 mHz). There have been arguments that all living cells spontaneously exhibit Bokkon-type ~10-12 W·m-2 ultraweak photon emissions (UPE) independent of temperature-based Arrhenius reactions. However the non-Gaussian distribution of the phasic voltage-photon events can be accommodated by the results of accelerating mass equivalents of resting photons into the time frame of single electron orbits which would require ~38 s. This condition is strongly dependent upon the presence of free protons within Pollack’s interfacial water states. The duration associated with the energy from the magnetic moment of a proton in a 1 nT magnetic field generated by 2 pA currents through channels across the membrane when divided into Planck’s constant is ~38 s. Second shell activation energies (~10-20 J) that are correlated with proton movements within a human photoreceptor’s volume of water result in a rate constant that is equivalent to energy within the range of Cosmic Microwave Background. One solution to accommodate the median emission of ~2·10-12 W·m-2 as a mass volume within a cell, the equivalent magnetic field strength of 1 nT, the interconnected 10-20 J and the diffusivity coupled to the hydrogen line suggests UPE may be reverse reactions from all living mass originating as Popp’s primordial solar photon energy. If these convergence solutions are valid then non-local photon formation would be the source of these spontaneous shifts in photoreceptors that would be mediated by a plethora of local physical chemical manifestations.

Searching for Sterile Neutrinos and CP Violation: The IsoDAR and DAEδALUS Experiments

The IsoDAR experiment uses a novel isotope decay-at-rest (DAR) source of electron antineutrinos using protons from a 60 MeV cyclotron. Paired with a large neutrino detector (such as KamLAND or WATCHMAN), the experiment can observe hundreds of thousands of inverse beta-decay events and do a decisive test of the current hints for sterile neutrino. DAEδALUS is a phased program leading to a high-sensitivity search for CP violation. The experiment uses a set of high-intensity 800 MeV cyclotrons to produce pion DAR neutrino sources at several locations (1.5km, 8km, and 20km) going to a single ultra-large, underground detector with free protons such as Hyper-K. The DAEδALUS experiment will provide a high-statistics antineutrino data set with no matter effects that can be combined with long-baseline data sets to provide enhanced sensitivity to CP violation and matter effects.

Does the proton decay?

The free neutron is unstable. It can decay into a proton with emission of an electron and an electron antineutrino. The mean lifetime of the free neutron is about 15 minutes. In contrast, the free proton seems stable. To date, no proton decay has been observed. In this article, we discuss the possibility of proton decay within the Standard Model which describes the elementary particles and their interactions. With the grand unified theory that describes the elementary particles and fundamental interactions in higher energy range, we discuss the possibility of the proton decay. Some of theoretical predictions for free proton decay in extremely high energy range are given and compared with the estimated lower limits of the lifetime in recent experiments of the possible free proton decay.

Reduce the matrix effect in biological tissue imaging using dynamic reactive ionization and gas cluster ion beams.

In the context of a secondary ion mass spectrometry (SIMS) experiment, dynamic reactive ionization (DRI) involves introducing a reactive dopant, HCl, into an Ar gas cluster primary ion beam along with a source of water to enable dissociation of HCl to free protons. This concerted effect, precisely occurring at the impact site of the cluster beam, enhances the protonation of molecular species. Here, the authors apply this methodology to study the hippocampus and cerebellum region of a frozen-hydrated mouse brain section. To determine the degree of enhancement associated with DRI conditions, sequential tissue slices were arranged in a mirrored configuration so that comparable regions of the tissue could be explored. The results show that the protonated lipid species are increased by ∼10-fold, but that the normally prevalent salt adducts are virtually unaffected. This observation is discussed as a novel approach to minimizing SIMS matrix effects in complex materials. Moreover, the chemical images of protonated lipid ions exhibit clearer features in the cerebellum region as compared to images acquired with the pure Ar cluster beam.

Hybrid method to resolve the neutrino mass hierarchy bysupernova (anti)neutrino induced reactions

We introduce a hybrid method to determine the neutrino mass hierarchy by simultaneous measurements of responses of at least two detectors to antineutrino and neutrino fluxes from accretion and cooling phases of core-collapse supernovae. The (anti)neutrino-nucleus cross sections for 56Fe and 208Pb are calculated in the framework of the relativistic nuclear energy density functional and weak interaction Hamiltonian, while the cross sections for inelastic scattering on free protons p(ν̄e,e+)n are obtained using heavy-baryon chiral perturbation theory. The modelling of (anti)neutrino fluxes emitted from a protoneutron star in a core-collapse supernova include collective and Mikheyev-Smirnov-Wolfenstein effects inside the exploding star. The particle emission rates from the elementary decay modes of the daughter nuclei are calculated for normal and inverted neutrino mass hierarchy. It is shown that simultaneous use of (anti)neutrino detectors with different target material allows to determine the neutrino mass hierarchy from the ratios of νe- and ν̄e-induced particle emissions. This hybrid method favors neutrinos from the supernova cooling phase and the implementation of detectors with heavier target nuclei (208Pb) for the neutrino sector, while for antineutrinos the use of free protons in mineral oil or water is the appropriate choice.

Rapidity distribution of protons from the potential version of UrQMD model and the traditional coalescence afterburner

Rapidity distributions of both E895 proton data at AGS energies and NA49 net proton data at SPS energies can be described reasonably well with a potential version of the UrQMD in which mean-field potentials for both pre-formed hadrons and confined baryons are considered, with the help of a traditional coalescence afterburner in which one parameter set for both relative distance $R_0$ and relative momentum $P_0$, (3.8 fm, 0.3 GeV$/$c), is used. Because of the large cancellation between the expansion in $R_0$ and the shrinkage in $P_0$ through the Lorentz transformation, the relativistic effect in clusters has little effect on the rapidity distribution of free (net) protons. Using a Woods-Saxon-like function instead of a pure logarithmic function as seen by FOPI collaboration at SIS energies, one can fit well both the data at SIS energies and the UrQMD calculation results at AGS and SPS energies. Further, it is found that for central Au+Au or Pb+Pb collisions at top SIS, SPS and RHIC energies, the proton fractions in clusters are about 33$\%$, 10$\%$, and 0.7$\%$, respectively.

Assessment of H+ in complex aqueous solutions approaching seawater

pH measurements are used to assess both the free acidity of aqueous solutions and the concentrations, mi, of chemical species i related to hydrogen ion, H+, through chemical equilibrium, provided that measurements in reference solutions with well-known compositions are also carried out. Seawater is a highly complex electrolytic matrix of variable composition, rich in NaCl, where the determination of pH=−lg aH+ (aH+=mH+γH+ is the activity of the specified ion, H+ with the concentration mH+ and activity coefficient γH+≠1) is an issue of controversy.Electroneutrality prevents measurement of individual ion activity coefficients, which are affected and depend on the other ions in presence, namely the counter ions. Nevertheless, mean activity coefficients, γ±=γ+γ−, in this case γ±=γH+γCl−, can be experimentally assessed from the application of the Nernst equation to Harned cell (Pt|H2 vs. Ag|AgCl electrodes, without transference) in solutions of known mH+ and mCl−. In this work measurements of electrical potential, E/V, have first been taken in strategically planned solutions, ranging from 0.01molkg−1 HCl+(NaCl) to 0.01molkg−1 HCl+(NaCl+KCl+CaCl2+MgCl2), of ionic strength, I≈0.67molkg−1 at 15°C, 25°C and 35°C with experimental pressure corrected to reference pressure of 1atm. Mean activity coefficients were experimentally assessed with associated uncertainty. Further addition of sodium sulfate, Na2SO4, targeting artificial seawater (ASW), originates acid–base equilibria that affect the free hydrogen ion concentration, mH+. The changes introduced by the addition of sulfate in the measured Harned cell potential have been used to assess the free proton concentration and, based on the obtained results, to propose for the first time a procedure aiming to calculate values of bisulfate association constants with the corresponding uncertainty at 25°C for both studied media. Further, the effective ionic strength of artificial seawater (ASW) was calculated and compared with the value obtained using the salinity based equation largely conveyed in the literature.

Exclusive π−Electroproduction off the Neutron in Deuterium in the Resonance Region

The goal of our research is to provide the exclusive γ*(n) → p+π− reaction cross section from deuterium data using the correction factor that account for the final state re-scattering that can be determined from the data set itself. The “e1e” Jefferson Lab CLAS data set that we analyze includes both a hydrogen and deuterium target run period, which allows a combined analysis of pion electroproduction off the free proton, the bound proton, and the bound neutron under the same experimental conditions. Hence it will provide the experimentally best possible information about the off-shell and final state interaction effects in deuterium, which must be considered in order to extract the neutron information. This data set will provide results with a kinematic coverage for the hadronic invariant mass W up to 1.7 GeV and in the momentum transfer Q2 range of 0.4 − 1.0 GeV/c2. The cross section analysis of this data set is currently underway, which will considerably improve our knowledge of the Q2 evolution of π−p electroproduction cross sections off bound neutron needed for the extraction of excited neutron state electrocouplings for the first time.

Immobilization of Rare Earth Elements of the Mine Tailings Using Phosphates and Lime

Excessive exploitation of rare earth mines produced a great deal of mine tailings which needs proper treatment. High concentration of the total rare earth elements (REEs) (685.8 ± 48.7mg/kg) still existed in the mine tailings, which was more than 3 times as much as the average background concentration of China. More importantly, 88.8% of the REEs fractionated in exchangeable fraction under sequential extraction analysis, and 91.7% were leached under TCLP procedure, which indicated a high risk of leaching of REEs into the surrounding environment. Stabilization method was adopted to control the REEs leachability in the mine tailings. Soil incubation experiments were conducted to evaluate the effectiveness of soluble phosphates and lime in immobilizing REEs in the mine tailings. The results revealed that, with the addition of lime, the leachability of REEs reduced by 0.4%-18.3% with the addition of lime at 0.1%-1% (by weight). A more effective immobilization result was obtained with the addition of phosphates, as the REEs leachability reduced by 71.1%-98.4%. The sequential extraction analysis revealed that the lime treatment converted REEs in F1 into F2. In contrast, phosphate treatment converted the REEs into more stable fractions. The mechanism of the efficient immobilization of REEs with the soluble phosphates was described as follow: (1) Cation exchange between free proton or potassium ion and the soil bounded REEs; (2) Complexation and precipitation reactions between phosphate and REEs. In addition, the final pH value after soil incubation also influenced the effect of the immobilization of REEs.

Photoproduction of $ \pi^{0}$ -pairs off protons and off neutrons

Total cross sections, angular distributions, and invariant-mass distributions have been measured for the photoproduction of pairs off free protons and off nucleons bound in the deuteron. The experiments were performed at the MAMI accelerator facility in Mainz using the Glasgow photon tagging spectrometer and the Crystal Ball/TAPS detector. The accelerator delivered electron beams of 1508 and 1557MeV, which produced bremsstrahlung in thin radiator foils. The tagged photon beam covered energies up to 1400MeV. The data from the free proton target are in good agreement with previous measurements and were only used to test the analysis procedures. The results for differential cross sections (angular distributions and invariant-mass distributions) for free and quasi-free protons are almost identical in shape, but differ in absolute magnitude up to 15%. Thus, moderate final-state interaction effects are present. The data for quasi-free neutrons are similar to the proton data in the second resonance region (final-state invariant masses up to MeV), where both reactions are dominated by the decay. At higher energies, angular and invariant-mass distributions are different. A simple analysis of the shapes of the invariant-mass distributions in the third resonance region is consistent with strong contributions of an decay for the proton, while the reaction is dominated by a sequential decay via a intermediate state for the neutron. The data are compared to predictions from the Two-Pion-MAID model and the Bonn-Gatchina coupled-channel analysis.

Influence of water compartmentation and heterogeneous relaxation on quantitative magnetization transfer imaging in rodent brain tumors.

The goal of this study was to investigate the influence of water compartmentation and heterogeneous relaxation properties on quantitative magnetization transfer (qMT) imaging in tissues, and in particular whether a two-pool model is sufficient to describe qMT data in brain tumors. Computer simulations and in vivo experiments with a series of qMT measurements before and after injection of Gd-DTPA were performed. Both off-resonance pulsed saturation (pulsed) and on-resonance selective inversion recovery (SIR) qMT methods were used, and all data were fit with a two-pool model only. Simulations indicated that a two-pool fitting of four-pool data yielded accurate measures of pool size ratio (PSR) of macromolecular versus free water protons when there were fast transcytolemmal exchange and slow R1 recovery. The fitted in vivo PSR of both pulsed and SIR qMT methods showed no dependence on R1 variations caused by different concentrations of Gd-DTPA during wash-out, whereas the fitted kex (magnetization transfer exchange rate) changed significantly with R1 . A two-pool model provides reproducible estimates of PSR in brain tumors independent of relaxation properties in the presence of relatively fast transcytolemmal exchange, whereas estimates of kex are biased by relaxation variations. In addition, estimates of PSR in brain tumors using the pulsed and SIR qMT methods agree well with one another. Magn Reson Med 76:635-644, 2016. © 2015 Wiley Periodicals, Inc.

Probing shadowed nuclear sea with massive gauge bosons in the future heavy-ion collisions

The production of the massive bosons $Z^0$ and $W^{\pm}$ could provide an excellent tool to study cold nuclear matter effects and the modifications of nuclear parton distribution functions (nPDFs) relative to parton distribution functions (PDFs) of a free proton in high energy nuclear reactions at the LHC as well as in heavy-ion collisions (HIC) with much higher center-of mass energies available in the future colliders. In this paper we calculate the rapidity and transverse momentum distributions of the vector boson and their nuclear modification factors in p+Pb collisions at $\sqrt{s_{NN}}=63$TeV and in Pb+Pb collisions at $\sqrt{s_{NN}}=39$TeV in the framework of perturbative QCD by utilizing three parametrization sets of nPDFs: EPS09, DSSZ and nCTEQ. It is found that in heavy-ion collisions at such high colliding energies, both the rapidity distribution and the transverse momentum spectrum of vector bosons are considerably suppressed in wide kinematic regions with respect to p+p reactions due to large nuclear shadowing effect. We demonstrate that in the massive vector boson productions processes with sea quarks in the initial-state may give more contributions than those with valence quarks in the initial-state, therefore in future heavy-ion collisions the isospin effect is less pronounced and the charge asymmetry of W boson will be reduced significantly as compared to that at the LHC. Large difference between results with nCTEQ and results with EPS09 and DSSZ is observed in nuclear modifications of both rapidity and $p_T$ distributions of $Z^0$ and $W$ in the future HIC.

Measurement of theΣbeam asymmetry for theωphotoproduction off the proton and the neutron at the GRAAL experiment

We report on new measurements of the beam asymmetry for \omega\ photo-production on proton and neutron in Hydrogen and Deuterium targets from the GRAAL collaboration. The beam asymmetry values are extracted from the reaction threshold (E_{\gamma} = 1.1 GeV in the free nucleon kinematics) up to 1.5 GeV of incoming photon energy. For the first time both the radiative and the three-pion decay channels are simultaneously investigated on the free proton. Results from the two decay channels are in agreement and provide important constraints for the determination of resonant state contributions to the \omega\ production mechanism. First experimental results on the deuteron allow the extraction of the \Sigma\ beam asymmetry on quasi-free nucleons. Comparison of the results for free and quasi-free kinematics on the proton shows a generally reasonable agreement, similar to the findings in pseudo-scalar meson photo-production reactions. For the first time measurements on quasi-free neutrons are available, showing that both the strength and the angular distributions of the beam asymmetry are sensibly different from the results on the proton target.

Structural Study of Plasticized Carboxy Methylcellulose Based Solid Biopolymer Electrolyte

Carboxyl methylcellulose (CMC) doped with oleic acid (OA) and plasticized with glycerol was able to be produced into solid biopolymer electrolytes using the solution cast technique. The CMC-OA-glycerol solid polymer electrolyte obtained the highest conductivity of 1.64 x 10-4 S cm-1 at room temperature for sample Gly 40 wt. %. Within the temperature range investigated, the conductivity– temperature relationship of the biopolymer electrolytes is characteristically Arrhenius behaviour, suggesting that the conductivity is thermally assisted. Fourier Transform Infrared studies was carried out to determine the dissociation of free protons (H+) from the carboxyl group (–COOH) of glycerol.

Mass-splitting effect on flows in heavy-ion collisions in the Fermi-energy domain

In this work, based on one updated version of the ultrarelativistic quantum molecular dynamics (UrQMD) model in which the Skyrme-like (parabolic) isospin- and momentum-dependent interaction is included, the effect of the neutron-proton effective mass splitting (NPEMS) on flows in heavy-ion collisions at the Fermi-energy domain (between 40 and 100 MeV/nucleon) is focused. Using various Skyrme interactions (all exhibiting similar values of isoscalar incompressibility but very different NPEMS), both rapidity- and transverse-momentum-dependent directed and elliptic flows of free neutrons and protons are calculated. Our calculations show that the effect of NPEMS on the flows of free nucleons is more obvious at ${E}_{\mathrm{lab}}=100\phantom{\rule{0.16em}{0ex}}\mathrm{MeV}/\mathrm{nucleon}$ than at $40 \mathrm{MeV}/\mathrm{nucleon}$. At ${E}_{\mathrm{lab}}=100\phantom{\rule{0.16em}{0ex}}\mathrm{MeV}/\mathrm{nucleon}$, the directed flows of both neutrons and protons are easily affected by the NPEMS, while the elliptic flow of protons is not very sensitive to the NPEMS at both energies. It is suggested that the directed flow is better than the elliptic flow for probing the NPEMS.