Jayakumar R. Particle Accelerators, Colliders, and the Story of High Energy Physics: Charming the Cosmic Snake

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YITP-07-99, “A particle God does not want discovered”, Jonathan Leake, The

Sunday Times, Oct 18, 2009). There is an interesting hypothesis in this paper,

which is not unscientiﬁc in its approach. They propose that if the quantity called

“action” is taken to be a complex quantity (albeit arbitrarily and contrary to past

experience), we get a result that all actions become nonlocal and make certain

that trajectories of events will become improbable [In general mechanics, the

well-veriﬁed law is that action, which is the integral of the Lagrangian (differ-

ence between kinetic energy and potential energy) over time, is a minimum for

the trajectory that is actually observed. This is the equivalent of stating that the

shortest distance between two points is given by a straight line. In simpler terms,

Nature is frugal]. By hypothesizing an action that is complex, Nielsen and

Ninomiya show that certain small action trajectories, which would have been

most probable, end up with low probabilities. They speculate that one such

trajectory is the discovery of the Higgs boson. They go on boldly to speculate

that nature, in preventing the discovery of the boson, will choose to cause an

irrepairable accident in LHC. Literally what this means is that the discovery will

be so destructive in the future (after discovery) that the Higgs boson will travel

back in time and destroy the machine, before the very proton beam collision.

Although this “unorthodox” idea sounds interesting and scientiﬁc and is even

suggestive of nonlocal quantum effects, the fundamental basis for a complex

action is untenable. In the vast experience of physics theory and experiments,

there is no evidence for a complex action or for backward causation in time, and

neither does it resolve any existing physics issues to make this approach a

worthy one. The idea that the Higgs will thwart its own discovery is untestable.

Above all, this could have been foretold for the discovery of quark, which did

happen and no machin e was broken. Given all these, this speculation, even if

valid, is extremely improbable and not worth worrying about.

The authors have now revised their approach to say how LHC may be run

(using “a card-drawing experiment”) so that success may be assured.

• Mini Black Hole

There have been observations that conﬁrm the existence of black holes in the

Universe. Black holes are massive star-like objects whose density of matter is so

high that their gravity is intense and they pull in any neighboring matter. Space is

so curved around them that radiation (light) is bent around them and even light

cannot escape. A popular fear was created that LHC with its intense concentra-

tion of energy will produce mini black holes which would escape the machine.

The scenario would then go on to the mini black hole burrowing through earth,

devouring it and then beyond.

Ordinarily, below the Planck energy of 10

eV, one would not expect to

produce black holes, but N. Arkani-Hamed, S. Dimopoulos, and G. Dvali (ADD)

published a paper in 1998 which showed that if extra dimensions exist as is

postulated in the String theory (Russell–Sundr um model), the threshold energy

would be reduced to a TeV or so, since gravity incr eases much faster with

decreasing distance in the extra dimensions than the inverse square law observed

by matter in 3 dimensions. The particles, we have observed so far, are 3

Sociological Impact of the LHC Project 215

dimensional, but a high energy of collisions could produce particles that exist in

multi-dimensional space, and the ADD model predicts the formation of mini

black holes. Other calculations by S. B. Giddings and S. Thomas also show that

the black hole formation in LHC collision has a very low but ﬁnite probability,

and obviously, only if the physics model is valid. But the public commentary on

this has centered on the safety of the LHC machine and whether LHC mini black

hole will cause a catastrophe.

First, why such a scenario is unlikely: In its 4.5 billion years of existence, the

earth has been bombarded by cosmic rays of energy up to 10 million times that

of LHC protons. Even granting that the target of the cosmic rays is ﬁxed

(meaning it is not a head-on collisio n of particles), the equivalent energy is up

to thousand times that of the LHC beam. In its life, the earth has seen more than

3  10

collisions with such energies, while LHC will create only 10

collisions in its operational lifetime. In the scale of solar system, there have

been over 3  10

collisions of high energy, a billion or more times than LHC

will observe. Including astronomical bodies such as planets and stars, which also

have existed for billions of years, nature has carried on trillion times LHC-type

collisions. But the phenomenon of creation of destructive earth-devouring black

hole has not occurred in known history of the earth and the solar system, and

neither are there any observations of mini black holes in the Universe. All

leading scientists like Steven Hawking have assessed the situation and come to

the same conclusion. Hawking states, “The world will not come to an end when

the LHC turns on. The LHC is absolutely safe... Collisions releasi ng greater

energy occur millions of times a day in the earth’s atmosphere and nothing

terrible happens.”

One reason we do not see mini black holes is that all black holes are theorized

to evaporate by the so-called Hawking Radiation. This radiation arises because

at the horizon of a black hole, beyond which matter and radiation cannot escape,

matter–antimatter pair would be produced from gamma rays, as in the vicinity of

any other high-energy object. At the horizon, often one of the pair (matter or

antimatter) may fall into the black hole, the other of the pair may escape, causing

energy loss to the black hole, which is termed as the Hawking Radiation. If born,

the LHC mini black holes would have a radius of 10

11

cm and temperature of

about 10

K, and such a black hole would evaporate within 10

24

s, well before

it gets out of the collision zone.

But one might argue that Hawking Radiation is not (yet) an observed fact and

an LHC black hole which is neutral might not interact, be “slippery,” and might

travel to the center of the earth. But if such black holes were to be produced and

lodged into the earth, the accretion rate of matter would be such that it would

take thousands of years. This reasoning, if pursued for dense matter like neutron

stars and white dwarfs, demonstrates a fallacy. The long life time of these stars

(billion years) precludes the existence of such long-lived mini black holes,

because the accretion rate for a black hole in a neutron star would be a few

years, and if mini black holes lived long, the neut ron stars would have become

black holes themselves.

216 13 The Snake Charmer: The Large Hadron Collider

The argument based on cosmic ray experience, much more powerful, and

earth and Universe’s long exposure also preclude the destructive creation of

objects like vacuum bubbles (expanding the lowest energy state of space) and

hypothetical magnetic monopoles which might convert ordinary proton into

electrons in a chain reaction.

• Strangelets:

We saw in the previous chapter that strange particles with non-integer spin have

three quarks of mixed ﬂavors. For example, the lambda baryon has an up, a

down, and a strange quark. Such quarks decay into normal matter with short

lifetimes. But it is hypothesized that strange particles with more number of

quarks and being the size of a nucleus, would be more stable than ordinary

nuclei. These “strangelets” are more stable because with the greater variety of

quantum numbers, Pauli’s exclusion principle (which forbids more than one

particle with same quantum numbers to occupy a given state) allows packing of

the ground state. If the surface tension of the strangelet nucleus is larger than a

critical value, then larger strangelets are even more stable (nuclei have forces

similar to liquid drops). Strangelets are candidates for dark matter. However, no

strangelets have been detected so far.

If indeed large strangelets exist with greater stability, then ordinary matter

coming in contact with strangelets might be converted to strange matter, and a

chain reaction might convert the whole earth into hot strange matter. Cosmic ray

strangelets, on the way to earth, would decay into positively charged particle and

be repelled by nuclei. But a collider could produce negatively charged

strangelets which would attract normal nuclei. However, even the Relativistic

Heavy Ion Collider, which has a higher probability of producing strangelets than

LHC, has not create d them.

In summary, the concept of the existence of stranglets has not been given

credence by any experim ental or astronomical observation. Even if these exist,

it is unknown if these are stable. If these exist and are stable, they are more likely

to be cold and positively charged (noninteractive). Therefore, all indications

point to this being not a safety issue.

As pointed out in the CERN report, the conclusion that the LHC does not pose

any serious safety issues is based on sound empirical reasoning and observations

and experimental results. Therefore, the conclusions also apply to future

speculations on other exotic phenomenon. In a lighter vein, no CERN physicist is

planning to relocate to Australia or Canada when LHC achieves full energy.

The Exploration of the Next Frontier Has Begun

Like Robert Wilson of the Fermilab, the scientists and engineers of the world have

become “Frontier Men and Women.” Though we might be unable to explore all

physical frontiers, there would always be frontiers to explore in science. The LHC,

Sociological Impact of the LHC Project 217

with its successful startup, promises to at least give a glimpse of the predicted and

unforeseen physics results. Even with the presently achieved colli sions, these new

revelations have started pouring in. Since the commissioning of LHC, these are

some of the new results, that show that we are at a new frontier

• The LEP Collider at CERN results showed that the Higgs boson has to have a

rest mass greater than 114 GeV/c

. The Fermilab Tevatron experiments

excluded the range of 158 GeV/c

– 175 GeV/c

. Now, with record collision

energies (3.5 TeV on 3.5 TeV), LHC (ATLAS and CMS) results show that the

Higgs rest mass cannot be in the range of 150 GeV/c

– 205 GeV/c

. (These are

stated with 90–95% conﬁdence level).

• The LHC

surpassed the precision with which Tevatron investigated matter-

antimatter asymmetry using B mesons. LHC

has discovered that the matter-

antimatter imbalance is not as strong as Tevatron results indicated and has set the

upper limit of 4 times the prediction of the Standard Model. While this is a

positive for the Standard Model, the issue of accurate determination of matter-

antimatter symmetry in the Universe will require more work.

• The ATLAS results, though have not found any evidence of supersymmetric

particles, but have been able to determine the lower limit on the ratio of the

squark mass to gluino (super partner of gluon) mass. This indicates that the super

particles, if they exist, would have masses 900 GeV/c

or higher. This would

mean that they would be produced very rarely and lot of events would have to be

recorded before any conclusions can be drawn.

• Using lead ion collisions, the ALICE detector observed that the quark-gluon

soup behaves like an ideal ﬂuid.

In 2012, when the machine reaches the full energy, there would be breathless

anticipation of results. The coin has been dropped into the vending machine and the

child in us is eagerly waiting for the treats. The LHC is the culmination of human

endeavor of several centuries in modern science. The shoulders of all the past

accelerator and dete ctor builders and theoretical physicists are supporting this

endeavor. The effort combines the advances in physics, engineering, mathematical

knowledge, the development of many materials from ordinary metals to exotic

alloys and polymers, and the latest developments in information technology. Above

all, it brings forth the extraordinary spirit of exploration and cooperation that drives

us all and the wisdom to direct this spirit in a fruitful journey.

218 13 The Snake Charmer: The Large Hadron Collider

Index

Accelerator, 2, 36

facilities, 141, 183

AGS. See Alternating gradient synchrotrons

Alpha decay, 15, 16, 32

Alpha particles, 15–19, 24, 25, 29, 32, 36, 38,

39, 53, 55, 77, 78

Alternating gradient synchrotrons (AGS),

90–95, 99, 103, 109, 110, 115, 119, 155,

167, 175

optical analogy, 93

focusing concept, 93, 98

strong focusing, 94

Antiproton, 87–90, 128, 129, 151,

174–179, 203

discovery, 87, 89–90

production and storage, 129

Asymptotic freedom, 165–166

Atomic models

Bohr, N., 21, 22

plum pudding, 11, 18, 19

Rutherford, E., 20, 22

Atomic structure, 18–20, 116

Atomist concept, 1, 3

Beam dynamics

Hills equation, 106

longitudinal, 105–106

transverse, 106–108

Beta decay, 16, 75, 97, 134, 160, 167–168

Beta rays, 14, 15, 153

Betatron, 6, 42, 56–60

condition, 59, 60

ﬁnal energy, 58

function, 107

oscillations, 60, 63–65, 85, 87, 91, 93,

99, 106, 180

tune, 108

Bevatron, 86–90

“B” factory, 207

Binding energy, 15

Black body radiation, 20–21

BNL. See Brookhaven National Laboratory

Brookhaven National Laboratory (BNL),

84–86, 92, 128

Cathode ray tube, 7, 9, 11, 21

Charge conjugation, 148–151, 155

Charm, 156, 166–168

Cloud chamber, 71, 72, 74–77, 88, 185

Cockroft–Walton generator, 36–40

Colliders

assembly, 176, 179–181

center of mass, 172, 208

concept, 41, 217

engineering systems, 183

interaction region (IR), 175, 181, 182, 201

scheme, 173–176

stochastic cooling, 178–179

storage rings, 173, 176–177, 203

Color, 156,160,165,166

angular momentum, 149, 150,167

baryon and lepton numbers,156

energy, 148

Conservation

mass, 3

momentum, 148,171

Cosmic rays, 11, 25–29, 53, 70–72, 75, 76, 78,

79, 84, 86, 88, 134, 212, 216, 217

variation with altitude, 76

R. Jayakumar, Particle Accelerators, Colliders, and the Story of High Energy Physics,

DOI 10.1007/978-3-642-22064-7,

Springer-Verlag Berlin Heidelberg 2012

219

Coulomb’s Law, 18

C, P, T violation, 96, 150–156, 206, 207

Cyclotron, 39, 41, 44–47, 49–58, 78, 82, 91,

115–116

basic concept, 45

ﬁnal energy, 48

ﬁrst 80 keV, 49

11 inch, 49

27 inch, 50

60 inch, 50–52

principle, 47

TRIUMF 520 MeV, 53, 54

Dark matter and dark energy, 168, 199, 205,

206, 217

Detectors

assembly, 183, 185, 191, 192, 196, 212, 213

bubble chamber, 96, 185–187, 189

Cerenkov counters, 192–194, 213

Cerenkov, P.A., 89, 193, 194

cloud chamber, 71, 72, 76, 77, 183,

185, 186

collaboration, 185, 197, 212, 214

EM calorimeters, 194–195

Hadronic calorimeters, 195–197, 213

photographic plates, 77, 78, 183

photomultiplier tubes, 190, 191

pixel, 191, 192, 196, 213

proportional counters, 16, 188–190

scintillation, 17, 18, 89, 189, 190, 194

scintillators, 17, 38, 190, 195, 196, 213

silicon, 190–192, 196, 213

Dispersion function, 107

Electron

charge to mass ratio, 8, 9, 189

discovery, 8

Electroscope, 26–28, 77

Emittance, 107, 108

EM wave equation, 6

Energy loss in medium, 15

European council for nuclear research (CERN)

beginnings, 97

ﬁrst accelerator SC, 56, 97, 99

proton synchrotron (PS) 25 GeV, 102, 209

super proton synchrotron (SPS), 114, 202

synchrocyclotron (SC) 600 MeV, 84, 97,

99, 179

Fermi national laboratory

beginnings, 104, 108, 110, 142

Fermi Main Ring, 108, 119, 128, 176, 177

Ferrites, 85

Field index, 64, 83, 90, 91, 93,103

Fluorescence, 12, 192

FODO cell, 104, 106–108, 128, 130, 180, 209

half cell, 180

Gamma transition, 100–103, 114

Gauge transformation, 156–159

Geiger counter, 16, 24, 72, 188

The Gluon, 166, 169, 175, 212

Grand Uniﬁcation Theory (GUT), 87, 160, 205

Hadron Elektron Ring Alnalge (HERA), 124,

128–130, 200

Hess, V., 26

Higgs boson, 163, 169, 202–206, 211, 214, 215

Higgs ﬁeld, 163, 169

Large Hadron Collider (LHC), 123, 124, 174,

183, 195–197, 199–218

accelerator ring, 209–211

approval, 203

ATLAS, 195, 204, 208, 211–213

backward causation, 214, 215

Compact Muon Solenoid (CMS), 195–197,

208–209, 211–213

layout, 210, 214

LHCb, 214

magnets, 123

mini black holes, 215–216

objectives, 152–153

strangelets, 217

superconducting magnets, 128, 184, 200,

202, 203

tunnel, 184, 201–203, 210, 211

Lawrence, E., 39, 41, 44, 46, 49

LHC. See Large Hadron Collider

Linear accelerator

Alvarez linac, drift tube linac, 138,

142–143

klystron, 140–142, 144, 182

220 Index

Mark II and Mark III, 141, 142

RFQ, 138, 139

SLAC design, 143, 145

Sloan’s Linac, 49, 131–133

Stanford linear accelerator (SLAC), 43,

110, 142–145, 165, 169

Wideroe Linac, 42, 43, 46, 131, 135

Longitudinal focusing, 49, 100–103, 137, 177

Luminosity, 175, 176, 180, 200, 201, 203, 208

Magnet

basic designs, 119–124

cryostat, 123

dipole cosine, 120, 121

quadrupole, 120, 121

superconducting magnet fabrication,

117, 121, 200

Matter-antimatter imbalance, 206–208

Matter wave, 68

Maxwell’s equation, 5, 6, 20, 57, 62, 157

Mesons

confusion, 76

discovery, 77–79, 167

the eightfold way, 164, 187

proliferation, 78

Muons, 79, 97, 153–156, 168, 194–196,

212, 213

Neutrino, 79, 109, 151, 153, 155, 156, 164,

166–168, 196–197, 205

Neutron, 161, 165, 167, 168

discovery, 23–25, 39, 73

decay, 151, 156

Nuclear

ﬁrst observed reaction, 38

potential for a bomb, 25, 88

radius, 19, 75

Yukawa’s theory, 74–76

Operators, 68–70, 149–150

commutative, 150

Ouroboros, 199–200

Parity violation

Lederman experiment, 154

Lee and Yang proposal, 153

pion and theta particle, 149, 152, 155

Wu’s experiment, 153

Periodic table, 3

Phlogiston, 2–3

Photoelectric effect, 21, 24, 48, 190

Photographic plates, 12, 13, 17, 77, 78

Positron, 67–73, 75, 79, 88, 129–130, 149,

151, 160, 167

Dirac’s energy equation, 68, 70

discovery, 70–72

Proportional counter, 16, 17, 188–190

Proton, 19, 32, 44, 71, 85, 151, 168, 171, 187,

199

QCD. See Quantum chromo dynamics

QED. See Quantum electrodynamics

Quanta, 21

Quantum chromo dynamics (QCD), 96, 160,

165, 168, 169

Quantum electrodynamics (QED), 158, 165,

168, 205

Quark, 79, 96, 128, 155, 156, 159–161,

164–169, 174, 186, 207, 208, 217

discovery, 167

Quark-gluon plasma, 208, 211

Radioactivity, 11, 13–15, 27–29

alpha, beta, gamma rays, 14

Radiofrequency (RF) cavity, 82, 105, 124–128,

130, 177

superconducting, 127, 128, 130

Relativistic Heavy Ion Collider (RHIC), 84,

217

Rubbia, C., 203

Rutherford scattering, 18, 19

Schr

€

odinger equation, 22, 33, 34, 68–70

SM. See Standard model

Spontaneous symmetry breaking (SSB),

162–163

Mexican hat potential, 162, 163

SSC. See Superconducting supercollider

Stanford Linear Accelerator (SLAC), 140–145

Standard model (SM), 72, 79, 87, 147–169,

187, 199, 205–208

particle and force classiﬁcation, 96,

168, 205

Strange, 75, 152, 156, 164–168, 186, 187, 217

Index 221

Superconducting supercollider (SSC), 121,

123, 124, 179, 181, 182, 184, 197,

200–204, 214

Superconductors, 115–119, 123–126, 130,

162, 196

quench, 118

stabilization, 118, 119

strand, 118–119

superconducting alloys, 117

superconductivity, 116–117, 162

Supersymmetry (SUSY), 169, 206–208, 211

Symmetry, 147–169, 187, 206

breaking, 159, 160, 162–163, 206

invariance, 148–150, 158

parity, 148, 149–150

Synchrotron radiation, 60, 65–66, 83, 87, 96,

123, 125, 130, 145, 201

Synchrotrons, 45, 64–66, 81–116, 125, 128,

138, 167, 174, 176, 179, 180, 184,

185, 200

Cosmotron, 84

superconducting, 129, 130, 179, 200, 209

Tevatron, 108, 124, 128–130, 174, 175

Transformations, 15, 147–150, 152, 155–160

Tunnel, accelerator, 127, 184, 201, 202,

203, 211

Tunneling, 15, 32, 33, 35, 36, 39

Van de Graff generator, 39, 41

Violation

CP, 155, 206, 207

parity, 152–154

Wave function, 33–35, 68, 69, 158

Weak Interaction force, 16, 158, 161, 205

Wideroe, R., 41–43, 98, 131, 172

Wilson, R., 83, 108

W, Z bosons

discovery, 161

X-rays, 12–14, 17, 50, 65–66, 96, 114,

135, 145

222 Index