1. SELEX (SEGMENTED LARGE-X BARYON SPECTROMETER) Fermilab 96-97
11/29/2010
SELEX (SEGMENTED LARGE-X BARYON SPECTROMETER) Fermilab 96-97
11/29/2010
Emrah Tiras, University of Iowa
Emrah Tiras, Uni. of Iowa

2. Emrah Tiras, University of Iowa
11/29/2010
Outline
SELEX E781
Physical Goals of SELEX
SELEX Collaboration
SELEX Experimental Setup
Detector Overview
Spectrometers
Conclusion
11/29/2010
Emrah Tiras, University of Iowa
Emrah Tiras, Uni. of Iowa

3. 11/29/2010
SELEX
is a fixed target experiment at Fermilab which took data during the year 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.
11/29/2010
Emrah Tiras, University of Iowa
Emrah Tiras, Uni. of Iowa

4. Physical goals of the SELEX
The study of;
the lifetime of weakly decaying charmed baryons.
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.
11/29/2010
Emrah Tiras, 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)
11/29/2010
Emrah Tiras, 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.
11/29/2010
Emrah Tiras, University of Iowa

7. Schematic view of SELEX spectrometers
Hyperon Magnet X
Exit
M1 Magnet
M2 Magnet
M3 magnet
Targets
Beam Z
M1 spectrometer
M2 spectrometer
M3 spectrometer
Beam Spectrometer
Vertex Spectrometer
The beam spectrometer is between the exits of the hyperon magnet and target region. The vertex spectrometer is between the targets and M1 spectrometer. The M1,M2,M3 spectrometers are located after the corresponding analyzing magnets.
11/29/2010
Emrah Tiras, University of Iowa

8. Emrah Tiras, University of Iowa
SELEX Detector Layout
11/29/2010
Emrah Tiras, University of Iowa

9. Emrah Tiras, University of Iowa
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.
11/29/2010
Emrah Tiras, University of Iowa

10. Emrah Tiras, University of Iowa
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.
11/29/2010
Emrah Tiras, University of Iowa

11. Emrah Tiras, University of Iowa
Analyzing magnets
SELEX apparatus has 3 analyzing magnets that were used to measure track momentum.
Name Z
[cm]
Aperture
[cm]*[cm] B
[kG] Pt
[GeV] M1
190
61*51
11.98
0.73 M2
745
61*25
14.66
0.84 M3
4240
6.85
0.42
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Emrah Tiras, University of Iowa

12. Emrah Tiras, University of Iowa
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.
11/29/2010
Emrah Tiras, University of Iowa

13. Emrah Tiras, University of Iowa
Beam Spectrometer
is consisted of;
the hyperon production target
the hyperon magnet
the beam particle identification detectors
beam tracking detectors and
scintillators
11/29/2010
Emrah Tiras, University of Iowa

14. Emrah Tiras, University of Iowa
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)
11/29/2010
Emrah Tiras, University of Iowa

15. Emrah Tiras, University of Iowa
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)
11/29/2010
Emrah Tiras, University of Iowa

16. Emrah Tiras, University of Iowa
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
11/29/2010
Emrah Tiras, University of Iowa

17. Emrah Tiras, University of Iowa
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.
11/29/2010
Emrah Tiras, University of Iowa

18. Emrah Tiras, University of Iowa
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.
11/29/2010
Emrah Tiras, University of Iowa

19. Emrah Tiras, University of Iowa
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.
11/29/2010
Emrah Tiras, University of Iowa

20. Emrah Tiras, University of Iowa
Additional
42 graduate students in Physics completed their thesis with this experiment(data) from
8 graduate students from here.
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),
Production Asymmetry of Ds from 600 GeV/c Sigma⁻ and pi⁻ beam Physics Letters B 558 (2003),
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Emrah Tiras, University of Iowa

21. Emrah Tiras, University of Iowa
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] Chicago: Fermi National Accelerator Laboratory SELEX Collaboration; 2003 [cited 2003 Aug 8]. Available from:
High Energy Physics Division (HEPD) of Petersburg Nuclear Physics Institute (PNPI) of Russian Academy of Sciences [Internet] Russia: High Energy Physics Division; 2010 [cited 2010 Nov 1]. Available from:
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Emrah Tiras, University of Iowa

22. Emrah Tiras, University of Iowa
Thank you
for
listening to
my presentation…
Emrah Tiras
11/29/2010
Emrah Tiras, University of Iowa