SELEX ( SE GMENTED L ARG E - X BARYON SPECTROMETER) Fermilab 96-97

1. SELEX(SEGMENTED LARGE-X BARYON SPECTROMETER)Fermilab 96-97 EmrahTiras, University of Iowa

2. Outline • SELEX E781 • Physical Goals of SELEX • SELEX Collaboration • SELEX Experimental Setup • Detector Overview • Spectrometers • Conclusion EmrahTiras, University of Iowa

3. SELEX • is a fixed target experiment at Fermilab which took data during the year 96-97 with 600 GeV Σ−, π− • during two years of running it recorded 15.2 billion hadronic interaction events. • is a multistage charged particle spectrometer with high acceptance of Feynman X- Parameter. EmrahTiras, University of Iowa

4. Physical goals of the SELEX • The study of; • the lifetime of weakly decaying charmedbaryons. • the charmed baryon production in the 600 GeV hyperons' beam. • the excited baryons. • the charm baryon semileptonic decay. • charm baryon spectroscopy • both charm and non-charm physics. EmrahTiras, University of Iowa

5. SELEX Experiment Collaboration • 125 participants from 20 institution in 11 countries(USA, Russia, Turkey, Brazil, China, Germany, Israel, Mexico, UK and Italy) EmrahTiras, University of Iowa

6. The SELEX Experiment Setup • is consisted of; • a beam line • a target area • a multistage spectrometer • The SELEX experiment used the Fermilab charged Hyperon beam which is composed of 50% Σ⁻ and 50% π⁻ with the energy of about 600 GeV for negative polarity; and 92% p and 8% π⁺ with the energy of 540 GeV for positive polarity. • The beam was run at the forward production angle(Θ=0˚) • The experiment was designed to have high acceptance and resolution in Xf region 0.1<Xf<1. EmrahTiras, University of Iowa

7. Schematic view of SELEX spectrometers EmrahTiras, University of Iowa

8. SELEX Detector Layout EmrahTiras, University of Iowa

9. Detector Overview 1(The SELEX Exp. had an extensive particle identification system) • Vertex Silicon Strip Detector (SSD): The heart of the experiment with 4 µm transverse position resolution at 600 GeV. • Beam Transition Radiation Detector(TRD): Beam particles (Σ⁻/π⁻, p/π⁺) were tagged • 3000 phototube Ring Imaging Cherenkov Counter (RICH): identify the secondary particles: electrons, muons, pions, kaons, protons, and even hyperons. EmrahTiras, University of Iowa

10. Detector Overview 2 • The Electron Transition Radiation Detector (ETRD): to separate electrons from hadrons which is important for the semileptonic decay physics. • Three lead glass detectors: to identify and measure the energy of the photons and electrons. • SELEX also has a precise tracking system and 3 analyzing magnets to measure particle momentum. Emrah Tiras, University of Iowa

11. Analyzing magnets • SELEX apparatus has 3 analyzing magnets that were used to measure track momentum. Emrah Tiras, University of Iowa

12. SPECTROMETERS • The SELEX experiment was composed of five stage spectrometer • Beam • Vertex • M1 • M2 • M3 • Each spectrometer other than Vertex which is designed to create high resolution tracking near target, contained a bending magnet. EmrahTiras, University of Iowa

13. Beam Spectrometer • isconsisted of; • the hyperon production target • the hyperon magnet • the beam particle identification detectors • beam tracking detectors and • scintillators EmrahTiras, University of Iowa

14. M1 Spectrometer • is made up of; • a magnet with 1.3 T magnetic field • which gives a transverse momentum. • 2 large area silicon micro-strip detectors (LASD) • measure the beam and primary and secondary vertex tracks. • proportional wire chambers (PWC) • measure the momenta of the tracks. • drift chambers (DC) • a photon calorimeter (Lead Glass Electromagnetic Calorimeter) EmrahTiras, University of Iowa

15. M1 Spectrometer • was designed to analyze the particles from 2.5 to 15 GeV/c momentum range. • Low energy particles(from the vertex region) are tagged and photon energies are measured at this stage. • This plays a crucial role in measuring the momentum of upstream trucks. • This was built here (University of Iowa) EmrahTiras, University of Iowa

16. M2 Spectrometer • is consisted of; • a magnet with 1.5 T magnetic field. • LASDs • 7 PWCs with 2 mm wire spacing • 6 Vector Drift Chambers (explanation on the next slide) • 2 hodoscopes • 6 Electron Transition Radiation Detector(ETRD) • were designed to give good electron identification. • Ring Imaging Cherenkov (RICH) detector. • Provides the particle identification information for the hyperons' daughter particles. • is designed to identify particles with momentum higher than 15 GeV/c EmrahTiras, University of Iowa

17. M3 Spectrometer • is consisted of; • a magnet with 1.3 T. • 2 Multiwire Proportional Chambers(PWC) • 3 Vector Drift Chambers; • Were designed to provide the short track segments of downstream decay products, charged particles as well as the position information. • a photon Calorimeter • a neutron Calorimeter • was built jointly by the University of Iowa and the Trieste groups. Emrah Tiras, University of Iowa

18. Vertex Spectrometer • starts at the downstream end of the last target and ends at the middle of the M1 spectrometer. • is consisted of 20 Vertex Silicon Detectors(SSDs) mounted to five station, four SSDs at each. • the first 8 detectors, called 5 cm-detectors, have 20 µm pitch and 5.1*5.0 cm² active area. • The downstream 12 detectors, called mosaic detectors, have 25µm pitch and 8.3*3.2 cm² active area. • Each of the detectors has greater than 98% hit detection efficiency and spatial resolution about 6.5 µm. EmrahTiras, University of Iowa

19. Conclusion • First time the doubly charmed baryon Ξcc⁺ was interpreted from the experiment: Ξcc⁺ Λc⁺K⁻π⁺ • In 2002, the SELEX collaboration published evidence of a doubly charmed baryon Xi (Ξcc), containing two charm quarks. • They figured out a new particle decaying in two modes: • DsJ ⁺ D˚K • DsJ ⁺ Dsη • New measurements for D˚ and D⁺ lifetimes • τ₁: (409.6±1.1±1.5)fs • τ₂: (1039.4±4.3±7.0)fs • Precision measurements of the Ξc⁺ and D˚ and Ds lifetimes. • Production asymmetry of Ds from 600 GeV/s Σ and π beam. • At that time all these new experimental data had good agreement with theory. EmrahTiras, University of Iowa

20. Additional • 42 graduate students in Physics completed their thesis with this experiment(data) from 1997-2010. • 8 graduate students from here. • http://www-selex.fnal.gov/documentation/thesis • Some useful articles about the experiment. • Precision measurements of the [Lambda]c⁺ and D˚ lifetimes Phys. Rev. Let. 86, 5243 (2001). • Measurement of the Ds lifetime Physics Letters B 523 (2001), 22-28. • Production Asymmetry of Ds from 600 GeV/c Sigma⁻and pi⁻ beam Physics Letters B 558 (2003), 34-40. EmrahTiras, University of Iowa

21. References • Akgun, U.: CMS HF Calorimeter PMTs and Ξc+ Lifetime Measurement (University of Iowa, 2003) • Ayan, A.S.: The CMS Forward Calorimeter Prototype Design Studies and Ωc0 Search at E781 Experiment at Fermilab (University of Iowa, 2004) • Fermi National Accelerator Laboratory [Internet]. 2003. Chicago: Fermi National Accelerator Laboratory SELEX Collaboration; 2003 [cited 2003 Aug 8]. Available from: http://www-selex.fnal.gov • High Energy Physics Division (HEPD) of Petersburg Nuclear Physics Institute (PNPI) of Russian Academy of Sciences [Internet]. 2010. Russia: High Energy Physics Division; 2010 [cited 2010 Nov 1]. Available from: http://dbserv.pnpi.spb.ru/hepd/activities/hep.html EmrahTiras, University of Iowa

22. Thank you for listening to my presentation… EmrahTiras EmrahTiras, University of Iowa