LHeC に向けて - kek

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LHeC
に向けて

KEK

徳宿克夫

2008

1

12


protons

antiprotons

protons

protons

electrons?

12/Jan/2008

1

proton

nuclei

HERA:

(27.5 GeV

e

vs

920GeV

p)


LHeC

(70GeV e vs 7000GeV p)

LHeC

12/Jan/2008

2

歴史



Deep Inelastic Electron
-
Nucleon Scattering at the LHC




J.B. Dainton
,
M. Klein
,
P. Newman
,
E. Perez
,
F. Willeke


JINST 1 (2006) P10001


DIS2006 (
つくば)



J. Dainton
のトーク


2006

Advisory

Committee

が組織


2007

Steering

Group結成

10

26


初会合


2007

11

30


Open ECFA
ミーティングでの発表

(M.

Klein)


ECFA, CERN
のサポートが得られる。


WG結成に向けて、Convenorの人選中。

2008

9
月に
CERN
近辺で
ワークショップ。


2009
年末に

CDR


12/Jan/2008

3

ep


灰p
が同時に実験できるオプション以外はない。


電子加速器を建設する機会は
䱈L
アップグレードのときのみ



New physics, distance

scales few . 10
-
20
m

High precision

partons in LHC

plateau

Low x

parton

dynamics

High
Density

Matter

Large x

partons

Inclusive Kinematics for 70 GeV x 7 TeV



High mass

(Q
2
) frontier




Q
2

lever
-
arm

at moderate x




Low x (high W)

frontier

12/Jan/2008

4

LHC

対生成

LH
e
C

もともとある


クォークとレプトンから作れる


たとえば、
l
eptoquark


レプトンとクォークがあるなら、その両方の


性質をもった粒子もあっていいのでは?

Re + resonance

LHC
で発見された後、
LHeC
で狙いを定めて精密測定

12/Jan/2008

5

対生成の断面積は、
QCD


αs

とマスで決まる。

E
q
だと断面積はその
e
-
q
-
LQ
結合の強さに

よる。




Sensitivity
は残念ながら、
LHC
よりそう

優れているわけではない。

12/Jan/2008

6

Asymmetry

LHeC: 10 fb
-
1

per charge

LHC: single prod. 100 fb
-
1



= 0.1

e,


q

+

F =
-
1

F = +1

e+

e
-

q or q ?

_

q or q ?

_

しかし、見つかったあとで、
LQ

性質を調べるのには

LHeC

非常に有効

12/Jan/2008

7



New physics, distance

scales few . 10
-
20
m

High precision

partons in LHC

plateau

Low x

parton

dynamics

High
Density

Matter

Large x

partons

Inclusive Kinematics for 70 GeV x 7 TeV



High mass

(Q
2
) frontier




Q
2

lever
-
arm

at moderate x




Low x (high W)

frontier

12/Jan/2008

8

Event Rates: E
e

x 7000 GeV

100 fb
-
1

70 GeV

10 fb
-
1

140 GeV


electrons


positrons

Charged Currents

Neutral Currents

2 times E
e

compensates for 10 times the energy at highest Q
2

12/Jan/2008

9

High x
Partons



a
s

Full NC/CC sim (with systs)

& NLO DGLAP fit …


… high x pdfs


LHC discovery

& interpretation of new states?

… projected

a
s
precision f
ew/mil


(c.f. 1
-
2% now)

12/Jan/2008

10

Heavy Quarks

High precision c, b measurements

(modern Si trackers, beam

spot 15 * 35

m
2

, increased

rates at larger scales).


Systematics at 10% level



beauty is a low x observable!



s (& sbar) from charged current

bottom

(Assumes 1 fb
-
1

and

-

50% beauty, 10%

charm efficiency

-

1% uds


c


mistag probability.

-

10% c


b

mistag)

LHeC 10
o

acceptance

LHeC 1
o

acceptance

strange

(A. Mehta, M. Klein)

12/Jan/2008

11

12/Jan/2008

12

12

W, Z production :

really standard candles?


CTEQ 6.1
-
> 6.5:


Difference in HQ
treatment



Through the global fitting of PDF,




change in Gluon





change in Sea quark





Change in W
-
production @ LHC


Wu
-
Ki Tung @ DIS2007

LHC data help to improve PDF
.

Higgs


<
-
SM


MSSM
-
>

SUSY
のパラメータ領域では、


陽子の中の
b
-
クォーク分布が大きく効く場合もある。



―>

SUSY
パラメータの決定の上でも、重要になってくる可能性がある。

12/Jan/2008

13

Low x
Machine
としての
LHeC

HERA
からさらに
low
-
x

へ拡張できる。




ただし実験的には

非常に難しい。


電子のエネルギーが

高いために、
LowQ2
では

散乱角が非常に小さい。


179


―>

Q2

1GeV2


ただしルミノシティーは

たいしていらない。



Saturation
に答えを出せる

(か?)


INCREDIBLE

LOW x

COVERAGE!

12/Jan/2008

14

0

1

“pQCD” : parton evolution

“Hadronic”: Regge theory


behavior of γp total cross section

HERA
の場合

Donnachie & Landshoff

Gluck, Reya

and Vogt

Early ZEUS data showed rapid

increase of F
2

at low x.

Fixed

target

data

12/Jan/2008

15

F
2

構造関数の測定


x
が小さくなると
F
2

は急激に大きくなる


陽子の中には
soft ‘sea’
クォークがたくさん
ある


Q
2

が大きくなるにつれてその傾きは急
になっている。



softer parton smaller
resol.






dynamics of quarks and gluons



高い
x
では低エネルギーのデータとよく
つながっている。


DGLAP
発展方程式を使った
NLOQCD
はデータを非常に良く再現できている。

12/Jan/2008

16

12/Jan/2008

17

12/Jan/2008

18

FS04 Regge (~FKS): 2 pomeron model, no saturation

FS04 Satn: Simple implementation of saturation

CGC: Colour Glass Condensate version of saturation



LHeC
の場合

:
どの
Saturation
模型か?

Forshaw, Sandapen, Shaw

hep
-
ph/0411337,0608161

J. Forshow,
P. Newmann

Saturation model

毎の

違いを議論できるか?



―>
もっと
Study
が必要





!!

eA
も可能

!!

12/Jan/2008

19

どうやって

LHeC
を実現するか



Previously considered as `QCD

explorer’ (also THERA)




Reconsideration (Chattopadhyay

& Zimmermann) with CW cavities began




Main advantages: low interference

with LHC, E
e


140 GeV
, LC relation




Main difficulty: peak luminosity only

~0.5.10
32

cm
-
2

s
-
1

at reasonable power



First considered (as LEPxLHC)

in 1984 ECFA workshop




Recent detailed re
-
evaluation

with new e ring (Willeke)




Main advantage: high peak

lumi obtainable
(10
33

cm
-
2

s
-
1
)




Main difficulties: building it

around existing LHC, e beam life

LINAC
-
RING

RING
-
RING

ep


灰p
が同時に実験できるオプション以外はない。


電子加速器を建設する機会は
䱈L
アップグレードのときのみ

12/Jan/2008

20

Ring
-
Ring

Parameters

Top view

2 mrad

Non
-
colliding p beam

Vertically displaced



LHC fixes
p beam parameters




70 GeV electron beam, (compromise

energy v synchrotron


50 MW
)




M
atch e & p beam shapes, sizes




Fast separation of beams with

tolerable synchrotron power

requires finite crossing angle




2 mrad angle gives 8
s

separation at

first parasitic crossing




High luminosity running requires low
b

focusing quadrupoles close to interaction

point (1.2 m)


acceptance limitation to 10
o

of beampipe

12/Jan/2008

21

Ring
-
Ring Design



e ring would have to bypass experiments and P3 and 6



ep/eA interaction region could be in P2 or P8.

12/Jan/2008

22


alternative sites

6km

S. Chattopadhyay (Cockcroft), F.Zimmermann (CERN), et al.

Linac
-
Ring Design

(70 GeV electron beam at

23 MV/m is 3km + gaps)

Relatively low peak lumi, but good average lumi

Energy recovery in CW mode (else prohibitive power usage)

12/Jan/2008

23

Plenary ECFA, LHeC, Max Klein,
CERN 30.11.2007


Comparison
Linac
-
Ring and
Ring
-
Ring

Energy / GeV 40
-
140 40
-
80


Luminosity / 10
32

cm
-
2

s
-
1

0.5 10


Mean Luminosity, relative 2 1 [dump at L
peak

/e]


Lepton Polarisation 60
-
80% 30% [?]


Tunnel / km 6 2.5=0.5 * 5 bypasses


Biggest challenge CW cavities Civil Engineering


Ring+Rf installation


Biggest limitation luminosity (ERL,CW) maximum energy



IR not considered yet allows ep+pp


one design? (eRHIC) 2 configurations [lox, hiq]


e
±
p

Luminosity

Linac
-
ring

Ring
-
ring

Timeline



2007: form working groups + steering committee


initial meeting of conveners + committee



SAC overview



2007/8: ECFA/CERN endorsement “work out”



2008: workshop I



2009: workshop II


LH
e
C CDR [LHC Committee]



2011: LH
e
C TDR


-

construction 8 years
?


-

impact on LHC: civil engineering + installation



e
-
ring and
e
-
linac


-

be aware of CLIC progress

12/Jan/2008

26

Accelerator Experts

S.Chattopadhyay, R.Garoby, S.Myers, A. Skrinsky, F.Willeke


Research Directors

J.Engelen (CERN), R.Heuer (DESY), Y
-
K.Kim (Fermilab), P.Bond (BNL)


Theorists

G.Altarelli, S.Brodsky, J.Ellis, L.Lipatov, F. Wilczek


Experimentalists

A.Caldwell (chair), J.Dainton, J.Feltesse, R.Horisberger, A.Levy, R.Milner

Scientific Advisory Committee (SAC)


12/Jan/2008

27

12/Jan/2008

Steering Group


Oliver Bruening (CERN)

John Dainton (Cockcroft)

Albert DeRoeck (CERN)

Stefano Forte (Milano)

Max Klein
-

chair (Liverpool)

Paul Newman (Birmingham)

Emmanuelle Perez (CERN)

Wesley Smith (Wisconsin)

Bernd Surrow (MIT)

Katsuo Tokushuku (KEK)

Urs Wiedemann (CERN)


+ (increasing)

28

12/Jan/2008

Working Group Structure


Accelerator Design [RR and LR]


Interaction Region and Forward Detectors


Infrastructure


Detector Design


New Physics at Large Scales


Precision QCD and Electroweak Interactions


Physics at High Parton Densities [small x and eA]

Convenors
候補者にコンタクトを

取っているところ


―>

ぜひ参加を


29

Plenary ECFA, LHeC, Max Klein,
CERN 30.11.2007

Luminosity: Ring
-
Ring

10
33

can be reached in RR

E
e
= 40
-
80 GeV & P = 5
-
60 MW.


HERA was 1
-
4 10
31

cm
-
2

s
-
1

huge gain with SLHC p beam




F.Willeke in hep
-
ex/0603016:


Design of interaction region


for 10
33

: 50 MW, 70 GeV


May reach 10
34

with ERL in

bypasses, or/and reduce power.

R&D performed at BNL/eRHIC



I
e

= 100 mA

likely klystron

installation limit

Synchrotron rad!

10
33

cf also A.Verdier 1990, E.Keil 1986

Plenary ECFA, LHeC, Max Klein,
CERN 30.11.2007

Luminosity: Linac
-
Ring

LHeC as Linac
-
Ring version

can be as luminous as HERA II:


4 10
31

can be reached with LR:

E
e

= 40
-
140 GeV & P=20
-
60 MW

LR: average lumi close to peak


140 GeV at 23 MV/m is 6km +gaps


Luminosity horizon: high power:

ERL (2 Linacs?)



I
e

= 100 mA

High cryo load to CW cavities