Fast Nuclei, Hot Matter and Pyramids: The Physics of Colliders and Detectors

Chicago State University Colloquium

Edmundo García

March 12, 2008

Matter as a Philosophical Idea

• Democritus of Abdera

• All matter is composed of eternal, indivisible, indestructible and infinitely small quanta

• These atoms cling together in

different combinations to form the

objects perceptible to us.

uncutable

~ 460 B.C. - 370 BC

“Nothing exists exceptatoms and empty space,everything else is opinion”

atom: (a – tom)particles

interactions

universe

• These atoms cling together in

different combinations to form the

objects perceptible to us.

Our Actual Knowledge of Matter

1918

1897

1907

1997 (Fermilab) leptons

Experimental “discovery”

Why has this taken so long?

- Their size

How do we “see” small objects?

EM radiation or photons

dTo resolve the objects d ~

dimensionWave length of EM or particlewe use to “see”

dE

Ed

11

Energy of wave or particlewe use to “see”

“Looking” inside the Nature

Scale~ 0.1 nm

• Today’s best microscope is capable to resolve atoms

(~ d ~ 10-8 m) using EM radiation (X-Rays) E ~ 1 MeV

• In order to see subatomic structure we need to use more energetic radiation Use very fast particles (p = h /

Ernest Rutherford (1907)Atomic Nucleus Discovery

EeV

1918

1897

1907

2008 (LHC)

leptons

Experimental “discovery”

1997 (Fermilab)

Today’s Most Powerful “Microscopes”: Particle Colliders

p + p collisions at 14 TeVPb + Pb collisions at 5.5 TeV

The Large Hadron Collider

• Located in Switzerland/France Border

• Circumference 16.5 miles

• Four detectors used to study the collision

High Energy Particle Detectors

p + p collision

Au + Au collision

PbWO4

crystals

E. García 9

Data from “older” Heavy Ion Colliders

Elliptic Flow

Jet Suppression

High energy density

Applicability of thermodynamics

BRAHMS, Nucl. Phys. A757 (2005) 1-27

STAR, PRL 91, 072304

PHOBOS, Nucl. Phys. A757 (2005) 28

What is expected from the LHC?

• For p + p collisions the observation of Higgs boson is expected at the LHC This observation of which could confirm the predictions and 'missing links' in the

Standard Model of physics and could explain how other elementary particles acquire properties such as mass.

• In addition to the Higgs boson, other theorized novel particles that might be produced, and for which searches are planned, include

Strangelets Micro Black Holes Magnetic monopoles Supersymmetric

• For Pb +Pb collision further evidence of the formation of the Quark Gluon Plasma is expected

atoms

particlesnucleus

QGP

energy/density

Big quark-gluon p + n low mass nuclei neutral atom star dispersion of TODAY Bang plasma formation formation formation formation heavy elements

time 10-6s 10-4s 3 min 400,000 yr 109 yr >109yr 15x109yr

Copyright 1998 Contemporary Physics Education Project (CPEP)

time

Physics

Experiment as Collaborations

About 3000 people, 170 institutes , 36 countries

Research Opportunities: Software Development

• Many opportunities are open in software development: simulation and preparing the experiment for data analysis.

• In the simulation area this requires learning CAD design, to know the basis of how the detector works and to learn about models of how particles interact with matter

• In the analysis area this gives the opportunity to learn statistics methods, techniques in programming C++, and the process of digitization of the detector response.

• The development of analysis code is particularly important since usually leads to a physics study.

ZDC

Research Opportunities: Detector Upgrades Very High Momentum Particle Identification Detector for ALICE

• The LHC detectors are getting ready for data late 2008, so most of the original detectors are in place

• There are however opportunities for upgrades in the near future.

separation @ 3 separation @ 2

(dE/dx)

ALICE PID

Existing gap for detailed (> 3 hadron identification.

VHMPID

The challenge

• Relatively small detector covering ~ 5% of acceptance of ALICE’s central barrel

• 0.5 T magnetic field

• Particle identification in the range of 10 – 30 GeV

• Good separation resolution (~ 3• Enough granularity that allows the discrimination of background in a central HI

collision

VHMPID

VHMPID Geometry

• C5F12 gas radiator (n = 1.0015)

• Large area CsI photon-to-electron converter

• Position sensitive charged particle detector

• Multi wire proportional chamber (MWPC)

• Gas electron multiplier (GEM)

MWPC

GEM

photoelectron

Simulations and Project Status

• Simulations show the feasibility of the detector.

• The project is at the stage requesting grants to funding agencies (NSF, DoE) for the construction of a prototype.

• After the successful test of the prototype the full detector would be build (6 modules)

• This is a long term project that would open opportunities for students research at every stage

– Simulations– Design– Construction– Testing– Commissioning– Data Analysis

Research Opportunities: ApplicationsMeasurement of Cosmic Ray Flow to Find Chambers on Pyramids

• The objective is to develop a technique to search for chamber without excavation.

• Its based on the measurement of the flow of cosmic rays through the structure

Cosmic Rays

• The technique proposed is based on the detection of cosmic rays

• Cosmic rays are particles produced in the upper atmosphere, they hit the earth surface at a rate of one per square centimeter per second, at different energies and incident angles

• We are particularly interested in muons with large energies, these charged particles are able to penetrate about 30 m of limestone (15 GeV incident energy)

Cosmic rays to find chambers

• Imagine we have muons fired from many “guns” at a limestone with a cavity inside. If the muons do not have enough energy, most of them will be stopped in the limestone, except the ones that travel through less material, that is, through the cavity.

• By recording the position of the muons in a detector behind the lime stone and the number of hits (flux) we would be able to locate the cavity

detector

limestonecosmic rays

number of hits

5

10

45

39

10

6

8

7

Cosmic ray detection

• One way to detect muons is by using scintillating plastic.• This material produces small amounts of light when a electrically charged subatomic

particle travels through it• The light produced is then transported to a photosensitive device, this device converts the

amount of light into an electrical signal• The electrical signal is then digitized by another device, then stored in a computer for

subsequent analysis.

Light to electrical signal

electrical signalto digit 100101

11001

computer

Same principle can be applied to find cavities in pyramids, but in 3 dimensions

The detector in this case will be inside the pyramid, and by recording the position of the hits, the number of hits and the direction that they come from, we would be able to locate chambers present in the pyramids

Original Idea – proof of principle

Advantages of Modern Technology

• We would be able to search for chambers without excavation, that is without disturbing the structure

• We would be able to tell the position and size of the chamber within a given resolution (~ 90cm)

• The detection system would be reusable, that is once we take data in a given location we could take the detector to some other site

• This technique works, it was successfully used 30 years ago. We have the advantages of new technology, which will make the detector cheaper and more compact

• We have now a better understanding of the physics process and the computing power to predict the response of the detector by simulations. These simulations permit us to calculate variables such as resolution, number of events needed to make measurement, etc.

Simulations

• Have carried out extensive simulations using the computer application GEANT which calculates the physical processes that muons undergo when they transverse any type of material (limestone in our case).

Muons Energy:(a)15 GeV, (b) 20 GeV and (c) 25 GeV(d) Cumulative

• For the second round of simulations, the geometry used was the same, however two important changes were made:

– The detector size was of 1 m by 1 m

– The cosmic rays were generated in a hemisphere around the structure, and then thrown towards the arrangement at random azimuthal and zenith angles

• The tracks were then reconstructed from the characteristics of the hits in the detector. The muons were thrown at only one energy

• From this simulation we were able to detect also the chamber and discern its dimensions to first approximation

• Finalize Simulations

• Studying two methods to digitize the light from the scintillators, one is using a photomultiplier tubes, and the second one is using image intensifier with a charged couple device (CCD) camera.

• Build a prototype

• Request of funding agencies (NSF, National Geographic, Smithsonian Institute, Archeological Societies, etc.)

• There is a site (Chichen-Itza Main Pyramid) that is ideal to test detector and collect data, the director of the site supports the project.

Project Status/Plans

Main Pyramid Chichen-Itza

Backup Transparencies

The detector

In order to reconstruct the trajectory (track) of the cosmic rays in the lime stone we need to know the location of the hit in the detector in several planes

We propose a detector with 3 sets of 3 planes separated vertically about 1m

Each plane will consist of 75 cm long scintillator slats, we are currently investigating the optimal width and depth of the slat, if we find it to be say .5 by .5 cm the planes will have 125 slats (75 x 75 cm plane)

• This technique has advantages over the ground penetrating radar method (GPR)

– GPR has been used successfully to detect shallow graves only few meters below the surface

– For chambers under or inside a pyramid the GPR method does not work since to gain penetration, longer wavelength electromagnetic waves have to be used, loosing resolution

– The apparatus used for GPR needs to be put in the over site to be explored, which is not feasible for many pyramids

Current development

• We are currently measuring the amount of light from the scintillators and fibers. This information is critical because it will determine whether we use photomultipliers or a CCD to digitize the signals

• This measurement will also also determine the dimensions of the scintillators that we will use, which will have a direct impact in the height of the detector (for 1 cm by 1 cm scintillator rods the separation between the planes will give a ~ 2m height detector, and for a 0.25 by 0.25 cm scintillator rods ~ 1m height)

Forward Detection of Higgs (120 Mev)

• In non-diffractive production very hard, signal swamped with QCD dijet background

• Selection rule in central exclusive production (CEP) ~ JPC = 0++ improves S/B for SM Higgs dramatically

• Key: Detection of diffractively scattered protons inside of beam pipe. Plus: two collimated jets in central detector with consistent values mass from central detectors

• Acceptance for events in which both protons are measured in the 420 m detectors or in combination of 420 m + 220 m detectors (“Total”) • M. Albrow talk will be on the 420 m detectors.

Example: Central exclusive production

pp pHp with H (120GeV) bb

221 Ms

Can be reduced by:

Requiring correlation between ξ, M measured in the central detector andξ, M measured by the near-beam detectors

CEP of H(120 GeV) → b bbar:

1 2 s = M2

jets

RP220

M2jets/Mmm

CEP H(120) bb inclusive QCD di-jets + pu