Physics 663. Par t icle Physics Phenomenology. Apr il 18, Physics 663, lecture 3 1

Transcription

1 Physics 663 Par t icle Physics Phenomenology Apr il 18, 2002 Physics 663, lecture 3 1

2 Acceler at or s High I mpedance Micr owave Devices Super conduct ing Technology Elect r on Synchr ot r ons Elect r on Linear Acceler at or s St or age Rings Collider s Linear Collider s next Linear Collider Muon Collider VLHC Synchr ot r on Radiat ion Facilit ies Ref er ences: Donald H. Per kins, I nt r oduct ion t o High Ener gy Physics, Four t h Edit ion Ber gst r om and Goobar, Cosmology and Par t icle Ast r ophysics Physics 663, lecture 3 2

3 High-impedance Micr owave Devices EM cavit ies wer e invent ed as a way t o gener at e high volt age at moder at e input power Amplif ier s Oscillat or s Cavit ies Disk-loaded waveguides Physics 663, lecture 3 3

4 Klyst r ons The klyst r on was invent ed at St anf or d in The klyst r on ser ved as an oscillat or in r adar r eceiver s dur ing WW I I. Af t er t he war, however, ver y high-power klyst r ons wer e built at St anf or d f or use in t he f ir st linear acceler at or s. This opened t he way f or t he use of klyst r ons not only in acceler at or s and r adar, but also in UHF-TV, sat ellit e communicat ions, and indust r ial heat ing. Klyst r ons ar e high-vacuum devices based on t he int er act ion of a wellf ocused pencil elect r on beam wit h a number of micr owave cavit ies t hat it t r aver ses, which ar e t uned at or near t he oper at ing f r equency of t he t ube. The pr inciple is conver sion of t he kinet ic ener gy in t he beam, impar t ed by a high acceler at ing volt age, t o micr owave ener gy. Conver sion t akes place as a r esult of t he amplif ied RF input signal, causing t he beam t o f or m "bunches." These give up t heir ener gy t o t he high level induced RF f ields at t he out put cavit y. The amplif ied signal is ext r act ed f r om t he out put cavit y t hr ough a vacuum window. Physics 663, lecture 3 4

5 Super conduct ing Technology Super conduct ing mat er ials added t o t he t echnology base of acceler at or s Niobium-t it anium mult ist r and cables Niobium-t in f or higher f ields, but br it t le Niobium coat ings inside RF cavit ies now pr act ical and r eliable Physics 663, lecture 3 5

6 Elect r on Synchr ot r ons Limit ed by gr owing synchr ot r on r adiat ion ener gy r adiat ed per par t icle per t ur n since ener gy loss scales as m - 4, r adiat ion is (M/ m) t imes lar ger f or elect r ons t han pr ot ons LEP (E beam = 100 GeV) will be highest ener gy elect r on synchr ot r on 'E= 4 GeV This ef f ect mot ivat ed t he lar ge elect r on linac at SLAC Physics 663, lecture 3 6

7 Elect r on Linear Acceler at or s SLAC was built f or 25 GeV elect r ons wit h 240 klyst r ons shor t 2 micr osecond bur st s of int ense power at 60 Hz event ually exceeded 50 GeV by shor t ening t he pulse also 120 Hz Avoids synchr ot r on r adiat ion Loses advant age of mult iple passes in cir cular acceler at or Physics 663, lecture 3 7

8 St or age Ring SPEAR complet ed in met er diamet er E beam up t o 4 GeV char m discover ed in dedicat ed t o synchr ot r on r adiat ion Physics 663, lecture 3 8

9 The Lar gest Collider s Two lar gest and highest ener gy collider s ar e Fer milab Tevat r on (pr ot on/ ant ipr ot on wit h 1 TeV beam ener gy) CERN Ring LEP I I (elect r on/ posit r on wit h 100 GeV beam ener gy) Lar ge Hadr on Collider -LHC (pr ot on colliding wit h 7 TeV beam ener gy - t o t ur n on ar ound 2008) Physics 663, lecture 3 9

10 Linear Collider s Acceler at ion of elect r ons in a cir cular acceler at or is plagued by Nat ur e s r esist ance t o acceler at ion Synchr ot r on r adiat ion E = 4π/ 3 (e 2 β 3 γ 4 / R) per t ur n (r ecall γ = E/ m, so E ~ E 4 / m 4 ) eg. LEP2 E = 4 GeV Power ~ 20 MW For t his r eason, at ver y high ener gy it is pr ef er able t o acceler at e elect r ons in a linear acceler at or, r at her t han a cir cular acceler at or elect r ons posit r ons Physics 663, lecture 3 10

11 Linear Collider s Synchr ot r on r adiat ion E ~ (E 4 / m 4 R) Ther ef or e Cost (cir cular ) ~ a R + b E ~ a R + b (E 4 / m 4 R) Opt imizat ion R ~ E 2 Cost ~ c E 2 Cost (linear ) ~ ac L, wher e L ~ E cost Cir cular Collider Linear Collider Ener gy At high ener gy, linear collider is mor e cost ef f ect ive Physics 663, lecture 3 11

12 Linear Collider s The Fir st Linear Collider SLAC Linear Collider (SLC) next Linear Collider TESLA NLC/ J LC CLI C Physics 663, lecture 3 12

13 The Fir st Linear Collider (The SLC) This concept was demonst r at ed at SLAC (St anf or d Linear Acceler at or Cent er ) in a linear collider pr ot ot ype oper at ing at ~91 GeV (t he SLC) SLC was built in t he 80 s wit hin t he exist ing SLAC linear acceler at or Oper at ed pr ecision Z 0 measur ement s est ablished LC concept s Physics 663, lecture 3 13

14 The next Linear Collider T he next Linear Collider proposals include plans to deliver a few hundred fb -1 of integrated lum. per year TESLA J LC-C NLC/ J LC-X * design (1034 ) 3.4 o o 3.4 E (GeV) 500 CM o o 1000 Ef f. Gr adient (MV/ m) 23.4 o RF f r eq. (GHz) t bunch (ns) 337 o # bunch/ t r ain 2820 o Beamst r ahlung (%) 3.2 o o 8.8 Ther e will only be one in t he wor ld, but t he t echnology choice r emains t o be made * US and J apanese X-band R&D cooper at ion, but machine par amet er s may dif f er Physics 663, lecture 3 14

15 The next Linear Collider A plan f or a high-ener gy, highluminosit y, elect r on-posit r on collider (int er nat ional pr oj ect ) E cm = GeV Lengt h ~25 km ~15 miles Physics Mot ivat ion f or t he NLC Elucidat e Elect r oweak I nt er act ion par t icular symmet r y br eaking This includes Higgs bosons super symmet r ic par t icles ext r a dimensions Const r uct ion could begin ar ound and oper at ion ar ound (X) (S) (L) (UHF) Electron Injector RF Systems GHz GHz GHz GHz Positron Injector m ~10 m 170 m 510 m 200 m 10 m 560 m Pre-Linac 6 GeV (S) Compressor 136 MeV (L) ~5 km Pre-Damping Ring (UHF) 2 GeV (S) e Damping Ring e (UHF) e 9.9 km e+ 6 GeV (S) Target 2 GeV (L) 136 MeV (L) Compressor Pre-Linac 6 GeV (S) ~100 m 0.6 GeV (X) ~20 m Compressor e+ e+ Damping Ring (UHF) ~20 m ~100 m 9.9 km Low E Detector Electron Main Linac GeV (X) Positron Main Linac GeV (X) Compressor 0.6 GeV (X) not t o scale Final Focus Dump ~300 m Hi E Detector Dump Final Focus 8047A611 Physics 663, lecture 3 15

16 NLC/ J LC X Band RF Room t emper at ur e Electron Injector 560 m ~10 m 170 m Pre-Linac 6 GeV (S) Compressor 136 MeV (L) 2 GeV (S) e ~100 m 0.6 GeV (X) ~20 m Compressor Damping Ring e (UHF) Electron Main Linac GeV (X) 9.9 km (X) (S) (L) (UHF) RF Systems GHz GHz GHz GHz ~5 km Low E Detector Final Focus Dump ~300 m Hi E Detector Dump Final Focus Positron Injector 510 m 200 m 10 m 560 m Pre-Damping Ring (UHF) e 9.9 km e+ 6 GeV (S) Target 2 GeV (L) 136 MeV (L) Compressor Pre-Linac 6 GeV (S) e+ e+ Damping Ring (UHF) ~20 m ~100 m Positron Main Linac GeV (X) Compressor 0.6 GeV (X) not t o scale 8047A611 Physics 663, lecture 3 16

17 TESLA Super conduct ing RF Low t emper at ur e Physics 663, lecture 3 17

18 Time St r uct ur e Physics 663, lecture 3 18

19 CLI C (Compact Linear Collider) Physics 663, lecture 3 19

20 NLC Engineer ing Power per beam 6.6 MW cw (250 GW dur ing pulse t r ain of 266 nsec) Beam size at int er act ion 245 nanomet er s x 3 nanomet er s Beam f lux at int er act ion MW/ cm 2 cw (3 x GW/ cm 2 dur ing pulse t r ain) Cur r ent densit y 6.8 x A/ m 2 I nduced magnet ic f ield (beam-beam) 10 Tesla St abilize beam- beam induced bremsst rahlung - beamst rahlung Physics 663, lecture 3 20

21 Muon Collider Mot ivat ion: elect r on collider limit ed at high ener gy lengt h of linear collider -> $ beamst r ahlung - limit s L - but σ~ 1/ s so need L ~ s muons can be st or ed in a cir cular machine Pr oblems f or Muons unst able 2 x 10-6 secs -> γcτ ~ 6 x 10 2 γ met er s pr oduced as lar ge beam -> need t o f ocus Higgs Fact or y coupling t o Higgs ~ m f 2 4 x 10 4 x elect r on Physics 663, lecture 3 21

22 Muon Collider Physics 663, lecture 3 22

23 Muon Collider I onizat ion Beam Cooling Neut r ino Radiat ion Det ect or Radiat ion The Fut ur e f ir st st ep - neut r ino f act or y demonst r at es st or age and cooling Physics 663, lecture 3 23

24 Neut r ino Fact or y Physics 663, lecture 3 24

25 VLHC 100 TeV x 100 TeV since LHC = 14 TeV x 14 TeV Opt ions low f ield, lar ge r ing high f ield, small r ing Physics 663, lecture 3 25

26 Synchr ot r on Radiat ion Facilit ies A br oad spect r um of science has benef it ed f r om t he development of lar ge st or age r ings f or high ener gy physics sour ce of synchr ot r on r adiat ion init ially par asit ic oper at ion f r om HEP f acilit ies dedicat ed f acilit ies f ut ur e plans, such as LCLS Physics 663, lecture 3 26