Measurement of the Ds lifetime

We report precise measurement of the Ds meson lifetime. The data were taken by the SELEX experiment (E781) spectrometer using 600 GeV/c Sigma-, pi- and p beams. The measurement has been done using 918 reconstructed Ds. The lifetime of the Ds is measured to be 472.5 +- 17.2 +- 6.6 fs, using K*(892)0K+- and phi pi+- decay modes. The lifetime ratio of Ds to D0 is 1.145+-0.049.Comment: 5 pages, 2 figures submitted to Phys. Lett.

Confirmation of the Double Charm Baryon Xi_cc+ via its Decay to p D+ K-

We observes a signal for the double charm baryon Xi_cc+ in the charged decay mode Xi_cc+ -> p D+ K- to complement the previously reported decay Xi_cc+ -> Lambda_c K- pi+ in data from SELEX, the charm hadro-production experiment (E781) at Fermilab. In this new decay mode we observe an excess of 5.62 events over an expected background estimated by event mixing to be 1.38+/-0.13 events. The Poisson probability that a background fluctuation can produce the apparent signal is less than 6.4E-4. The observed mass of this state is (3518+/-3)MeV/c^2, consistent with the published result. Averaging the two results gives a mass of (3518.7+/-1.7)MeV/c^2. The observation of this new weak decay mode confirms the previous SELEX suggestion that this state is a double charm baryon. The relative branching ratio Gamma(Xi_cc+ -> pD+K-)/Gamma(Xi_cc+ -> Lambda_c K- pi+) = 0.36+/-0.21.Comment: 11 pages, 6 included eps figures. v2 includes improved statistical method to determine significance of observation. Submitted to PL

Measurement Of The Σ̄- Lifetime And Direct Comparison With The Σ+ Lifetime

We have measured the lifetime of the Σ̄- using the Fermilab Proton Center 375 GeV/c charged hyperon beam. We obtained (80.43±0.80±0.14) ps. We also measured the lifetime of the Σ+, obtaining (80.38 ±0.40±0.14) ps, in agreement with the Particle Data Group value. A direct comparison between the two lifetimes from the ratio of the decay curves gives a fractional lifetime difference of Δτ/τ=(-0.06±1.12)%, consistent with equal lifetimes for baryon and antibaryon as required by CPT invariance. ©1999 The American Physical Society.61314Foucher, M., (1992) Phys. Rev. Lett., 68, p. 3004Timm, S., (1995) Phys. Rev. D, 51, p. 4638Dubbs, T., (1994) Phys. Rev. Lett., 72, p. 808Caso, C., (1998) Eur. Phys. J. C, 3, p. 690(1993) GEANT 3.21 CERN Program Library W5103, , CERNKuropatkin, N., private communicationLangland, J.L., (1995) Hyperon and Antihyperon Production in P-Cu Interactions, , Ph.D. thesis, University of IowaMorelos, A., (1993) Phys. Rev. Lett., 71, p. 341

Total Cross Section Measurements With π- , Σ- And Protons On Nuclei And Nucleons Around 600 Gev/c

Total cross sections for Σ- and π- on beryllium, carbon, polyethylene and copper as well as total cross sections for protons on beryllium and carbon have been measured in a broad momentum range around 600GeV/c . These measurements were performed with a transmission technique in the SELEX hyperon-beam experiment at Fermilab. We report on results obtained for hadron-nucleus cross sections and on results for σtot(Σ-N) and σtot(π-N) , which were deduced from nuclear cross sections. © 2000 Elsevier Science B.V.57901/02/15277312Langland, J.L., (1995) Ph.D. Thesis, , University of IowaKleinfelder, S.A., (1988) IEEE Trans. Nucl. Sci., 35 (1)Dersch, U., (1998) Ph.D. Thesis, HeidelbergBiagi, S.F., (1981) Nucl. Phys. B, 186, pp. 1-21Bellettini, G., (1966) Nucl. Phys., 79, pp. 609-624Schiz, A.M., (1980) Phys. Rev. D, 21, pp. 3010-3022Murthy, P.V.R., (1975) Nucl. Phys. B, 92, pp. 269-308Caso, C., (1998) Eur. Phys. J. C, 3. , http://pdg.lbl.gov/1998/contents_plots.html, and data on total cross sections from computer readable filesSchiz, A.M., (1979) Ph.D. Thesis, , Yale University(1973) Landolt Börnstein Tables, 7. , Springer editionEngler, J., (1970) Phys. Lett. B, 32, pp. 716-719Babaev, A., (1974) Phys. Lett. B, 51, pp. 501-504Glauber, R.J., (1959) Boulder Lectures, pp. 315-413Franco, V., (1972) Phys. Rev. C, 6, pp. 748-757Karmanov, V.A., Kondratyuk, L.A., (1973) JETP Lett., 18, pp. 266-268Burq, J.P., (1983) Nucl. Phys. B, 217, pp. 285-335Gross, D., (1978) Phys. Rev. Lett., 41, pp. 217-220Beznogikh, G.G., (1972) Phys. Lett. B, 39, pp. 411-413Vorobyov, A.A., (1972) Phys. Lett. B, 41, pp. 639-641Foley, K.J., (1967) Phys. Rev. Lett., 19, pp. 857-859Fajardo, L.A., (1981) Phys. Rev. D, 24, pp. 46-65Jenni, P., (1977) Nucl. Phys. B, 129, pp. 232-252Breedon, R.E., (1989) Phys. Rev. Lett. B, 216, pp. 459-465Amos, N., (1983) Phys. Rev. Lett. B, 128, pp. 343-348Amaldi, U., (1977) Phys. Rev. Lett. B, 66, pp. 390-394Amos, N., (1985) Nucl. Phys. B, 262, pp. 689-714Akopin, V.D., (1977) Sov. J. Nucl. Phys., 25, pp. 51-55Amirkhanov, I.V., (1973) Sov. J. Nucl. Phys., 17, pp. 636-637Foley, K.J., (1969) Phys. Rev., 181, pp. 1775-1793Apokin, V.D., (1976) Nucl. Phys. B, 106, pp. 413-429Burq, J.P., (1982) Phys. Lett. B, 109, pp. 124-127Dakhno, L.G., (1983) Sov. J. Nucl. Phys., 37, pp. 590-598Kazarinov, M., (1976) Sov. Phys. JETP, 43, pp. 598-606De Jager, C.W., (1974) At. Data Nucl. Data Tables, 14, pp. 479-508Donnachie, A., Landshoff, P.V., (1992) Phys. Lett. B, 296, pp. 227-232Lipkin, H., (1975) Phys. Rev. D, 11, pp. 1827-1831Barnett, R.M., (1996) Phys. Rev. D, 54, pp. 191-192Carroll, A.S., (1979) Phys. Lett. B, 80, pp. 423-427Badier, J., (1972) Phys. Lett. B, 41, pp. 387-39

Total Cross Section Measurements with pi-, Sigma- and Protons on Nuclei and Nucleons around 600 GeV/c

Total cross sections for Sigma- and pi- on beryllium, carbon, polyethylene and copper as well as total cross sections for protons on beryllium and carbon have been measured in a broad momentum range around 600GeV/c. These measurements were performed with a transmission technique adapted to the SELEX hyperon-beam experiment at Fermilab. We report on results obtained for hadron-nucleus cross sections and on results for sigma_tot(Sigma- N) and sigma_tot(pi- N), which were deduced from nuclear cross sections.Comment: 42 pages, submitted to Nucl.Phys.

Nuclear Dependence Of Charm Production

Using data taken by SELEX during the 1996-1997 fixed target run at Fermilab, we study the production of charmed hadrons on copper and carbon targets with ∑ -, p, π -, and π + beams. Parametrizing the dependence of the inclusive production cross section on the atomic number A as A α, we determine α for D +, D 0, D s +, D +(2010), Λ c +, and their respective anti-particles, as a function of their transverse momentum p t and scaled longitudinal momentum x F . Within our statistics there is no dependence of α on x F for any charm species for the interval 0.1<x F <1.0. The average value of α for charm production by pion beams is α meson=0.850±0.028. This is somewhat larger than the corresponding average α baryon=0.755±0.016 for charm production by baryon beams (∑ -, p). © 2009 Springer-Verlag/Società Italiana di Fisica.644637644Cobbaert, H., (1987) Phys. Lett. B, 191, p. 456. , 10.1016/0370-2693(87)90639-3 1987PhLB.191.456CCobbaert, H., (1988) Phys. Lett. B, 206, p. 546. , 10.1016/0370-2693(88)91627-9Cobbaert, H., (1988) Phys. Lett. B, 213, p. 395. , 10.1016/0370-2693(88)91783-2 1988PhLB.213.395CLeitch, M.J., (2000) Phys. Rev. Lett., 84, p. 3256. , 10.1103/PhysRevLett.84.3256 2000PhRvL.84.3256L arXiv:nucl-ex/9909007Alessandro, B., Alexa, C., Arnaldi, R., Atayan, M., Baglin, C., Baldit, A., Beole, S., Willis, N., Charmonium production and nuclear absorption in p-A interactions at 450 GeV (2004) European Physical Journal C, 33 (1), pp. 31-40. , DOI 10.1140/epjc/s2003-01539-yAbt, I., (2009) Eur. Phys. J. C, 60, p. 525. , 10.1140/epjc/s10052-009-0965-7 2009EPJC.60.525A arXiv:0812.0734 [hep-ex]Heller, K.J., (1977) Phys. Rev. D, 16, p. 2737. , 10.1103/PhysRevD.16.2737 1977PhRvD.16.2737HSkubic, P., (1978) Phys. Rev. D, 18, p. 3115. , 10.1103/PhysRevD.18.3115 1978PhRvD.18.3115SAleev, A.N., (1987) Sov. J. Nucl. Phys., 46, p. 657. , [Yad. Fiz. 46, 1127 (1987)]Vecko, M., (1989) Czech. J. Phys. B, 39, p. 297. , 10.1007/BF01597781 1989CzJPh.39.297VAdamovich, M., (1992) Phys. Lett. B, 284, p. 453. , 10.1016/0370-2693(92)90460-L 1992PhLB.284.453AAlves, G.A., (1993) Phys. Rev. Lett., 70, p. 722. , 10.1103/PhysRevLett.70.722 1993PhRvL.70.722AAlves, G.A., (1994) Phys. Rev. D, 49, p. 4317. , 10.1103/PhysRevD.49.R4317 1994PhRvD.49.4317ALeitch, M.J., (1994) Phys. Rev. Lett., 72, p. 2542. , 10.1103/PhysRevLett.72.2542 1994PhRvL.72.2542LAdamovich, M., (1997) Nucl. Phys. B, 495, p. 3. , 10.1016/S0550-3213(97)00223-X 1997NuPhB.495.3AApanasevich, L., (1997) Phys. Rev. D, 56, p. 1391. , 10.1103/PhysRevD.56.1391 1997PhRvD.56.1391A arXiv:hep-ex/9702014Abt, I., (2007) Eur. Phys. J. C, 52, p. 531. , 10.1140/epjc/s10052-007-0427-z 2007EPJC.52.531A arXiv:0708.1443 [hep-ex]Duffy, M.E., (1985) Phys. Rev. Lett., 55, p. 1816. , 10.1103/PhysRevLett.55.1816 1985PhRvL.55.1816DVogt, R., The A dependence of open charm and bottom production (2003) International Journal of Modern Physics E, 12 (2), pp. 211-269. , DOI 10.1142/S0218301303001272Lourenco, C., Wohri, H.K., Heavy-flavour hadro-production from fixed-target to collider energies (2006) Physics Reports, 433 (3), pp. 127-180. , DOI 10.1016/j.physrep.2006.05.005, PII S0370157306001815Frawley, A.D., Ullrich, T., Vogt, R., (2008) Phys. Rept., 462, p. 125. , 10.1016/j.physrep.2008.04.002 2008PhR.462.125F arXiv:0806.1013 [nucl-ex]Russ, J.S., (1998) Proceedings of the 29th International Conference on High Energy Physics II World Scientific Singapore, 1259. , A. Astbury (eds), et al. arXiv:hep-ex/9812031Russ, J.S., (1998) Proceedings of the 29th International Conference on High Energy Physics, 2, p. 1259. , ed. by A. Astbury, et al. (World Scientific, Singapore) arXiv:hep-ex/9812031Engelfried, J., (1999) Nucl. Instrum. Methods A, 431, p. 53. , 10.1016/S0168-9002(99)00043-1 1999NIMPA.431.53E arXiv:hep-ex/9811001Kushnirenko, A., Alkhazov, G., Atamantchouk, A.G., Balatz, M.Y., Bondar, N.F., Cooper, P.S., Dauwe, L.J., Vishnyakov, V.E., Precision measurements of the ∧c+ and D 0 lifetimes (2001) Physical Review Letters, 86 (23), pp. 5243-5246. , DOI 10.1103/PhysRevLett.86.5243Garcia, F.G., (2002) Phys. Lett. B, 528, p. 49. , 10.1016/S0370-2693(01)01484-8 2002PhLB.528.49S arXiv:hep-ex/0109017Kaya, M., (2003) Phys. Lett. B, 558, p. 34. , 10.1016/S0370-2693(03)00246-6 2003PhLB.558.34S arXiv:hep-ex/0302039Brodsky, S.J., Kopeliovich, B., Schmidt, I., Soffer, J., (2006) Phys. Rev. D, 73, p. 113005. , 2006PhRvD.73k3005B arXiv:hep-ph/0603238Adamovich, M.I., (2003) Eur. Phys. J. C, 26, p. 357. , 10.1140/epjc/s2002-01073-6 2003EPJC.26.357WA. Blanco-Covarrubias, et al. (SELEX Collaboration), in preparatio

NeuLAND: The high-resolution neutron time-of-flight spectrometer for R3BR^{3}B at FAIR

NeuLAND (New Large-Area Neutron Detector) is the next-generation neutron detector for the R3B (Reactions with Relativistic Radioactive Beams) experiment at FAIR (Facility for Antiproton and Ion Research). NeuLAND detects neutrons with energies from 100 to 1000 MeV, featuring a high detection efficiency, a high spatial and time resolution, and a large multi-neutron reconstruction efficiency. This is achieved by a highly granular design of organic scintillators: 3000 individual submodules with a size of 5 7 5 7 250 cm3 are arranged in 30 double planes with 100 submodules each, providing an active area of 250 7 250 cm2 and a total depth of 3 m. The spatial resolution due to the granularity together with a time resolution of σt≤ 150 ps ensures high-resolution capabilities. In conjunction with calorimetric properties, a multi-neutron reconstruction efficiency of 50% to 70% for four-neutron events will be achieved, depending on both the emission scenario and the boundary conditions allowed for the reconstruction method. We present in this paper the final design of the detector as well as results from test measurements and simulations on which this design is based