LHC Forward Physics
Experiments:
ALICE
ATLAS
CMS
FP420 (R&D project)
LHCf
TOTEM
April 23, 2006
Jim Whitmore
Penn State University
DIS2006
XIV International Workshop on Deep Inelastic Scattering
Tsukuba, Japan, 20-24/April/2006
1
LHC Forward Physics
•Total cross-section (and luminosity) with a precision of 1%
•Elastic pp scattering
in the range: 10-3 < |t| = (p )2 < 10 GeV2
•Forward Physics:
•Low-x dynamics
•Diffractive phenomena:
•Soft and Hard
•Inclusive and exclusive Double Pomeron Exchange (DPE)
•Leading particle and energy flow in the forward direction
•pA, AA, gg and gp processes (sorry, I will not cover these topics)
Many of these topics can be studied best at startup luminosities
April 23, 2006
DIS2006
XIV International Workshop on Deep Inelastic Scattering
Tsukuba, Japan, 20-24/April/2006
2
“We are not studying a possibility of
forward physics with LHCb at the moment”
+LHCf
+TOTEM
April 23, 2006
+FP420
DIS2006
XIV International Workshop on Deep Inelastic Scattering
Tsukuba, Japan, 20-24/April/2006
3
Forward Detectors
General philosophy:
•Additional detectors near the IP
•Proton (Roman Pot) detectors:
*
•want to detect small scattering angles (~few mrad:)  min
K
•and the beam divergence

   
b*

b*
*
•so want large values of b*. However, luminosity
•want small b*
L
1
b
*
•So expect a selection of b* values (0.5-1540 m)
•RP detectors at 140-220 m from IP
•Need to go to 420 m → the “cold” region
April 23, 2006
DIS2006
XIV International Workshop on Deep Inelastic Scattering
Tsukuba, Japan, 20-24/April/2006
4
Roman Pot acceptance
M2=12s
- 240 m
FP420
TOTEM
(ATLAS)
 = proton momentum loss = Dp/p
Reconstruct  with roman pots
 < 0.1  O(1) TeV “Pomeron beams“
1
220m:
0.02 <  < 0.2
300/400m: 0.002 <  < 0.02
April 23, 2006
Detectors in the 420 m region are
needed to access the low  values
DIS2006
XIV International Workshop on Deep Inelastic Scattering
Tsukuba, Japan, 20-24/April/2006
(A. deRoeck)
Low b*: (0.5m): Lumi 1033-1034cm-2s-
5
TOTEM + CMS
Experimental
Apparatus
T1: 3.1 < h < 4.7
T2: 5.3 < h < 6.5
CMS Castor 5.25<h <6.5
IP5
10.5 m
T1
~14 m T2
CASTOR (CMS)
IP5
RP1 (147 m)
April 23, 2006
RP2 (180 m)
(later option)
DIS2006
XIV International Workshop on Deep Inelastic Scattering
Tsukuba, Japan, 20-24/April/2006
RP3 (220 m)
6
T1 Telescope
3.1< |h| <4.7
•
~3 m
•
•
•
T2 Telescope
5 planes with measurement of
three coordinates per plane.
3 degrees rotation and overlap
between adjacent planes
Primary vertex
reconstruction
Trigger with CSC wires
Digital r/o pads
5.3< lhl < 6.5
GEM (Gas Electron Multiplier)
Telescope: 10 ½-planes 13.5 m
from IP
Analog r/o circular strips
April 23, 2006
DIS2006
XIV International Workshop on Deep Inelastic Scattering
Tsukuba, Japan, 20-24/April/2006
7
Roman Pots
Test beam data:
reconstructed
tracks in y
Tracks
0
u,v
info
RP in SPS beam and the
detector is measuring the halo
BPM Roman Pot unit:
- Vertical and horizontal pots mounted as close as possible
- TOTEM at the RP: beam ≈ 80 mm
- Leading proton detection at distances down to 10beam + d
- Need “edgeless” detectors that are efficient up to the physical
edge to minimize “d”
- Currently two tech. (5-10 mm and 40-50 mm dead areas)
April 23, 2006
DIS2006
XIV International Workshop on Deep Inelastic Scattering
Tsukuba, Japan, 20-24/April/2006
8
Forward Detectors in ATLAS
Roman Pots at 240 m
Cerenkov Counter (LUCID)
= a lumi monitor at 5.4 <h< 6.1
+ neutral energy at zero degrees
(I. Efthymiopoulos)
IP1
April 23, 2006
DIS2006
XIV International Workshop on Deep Inelastic Scattering
Tsukuba, Japan, 20-24/April/2006
9
Running Scenarios
2
3
4
low |t|
elastic,
tot ,
min. bias,
soft
diffraction
diffraction
large |t|
elastic
hard
diffraction
large |t|
elastic
(under
study)
b* [m]
1540
1540
18
90
N of bunches
43
156
2808
156
N of part. per bunch
(x1011)
0.3
0.6 - 1.15
1.15
1.15
Half crossing angle
[mrad]
0
0
160
0
Transv. norm. emitt. [mm
rad]
1
1 - 3.75
3.75
3.75
RMS beam size at IP
[mm]
454
454 - 880
95
200
RMS beam diverg. [mrad]
0.29
0.29 - 0.57
5.28
2.4
Peak luminosity [cm-2 s-1]
1.6 x 1028
2.4 x 1029
3.6 x 1032
2 x 1030
Physics:
TOTEM
April 23, 2006
DIS2006
XIV International Workshop on Deep Inelastic Scattering
Tsukuba, Japan, 20-24/April/2006
(V. Avati, M. Deile)
1
Scenario
10
pp total cross section
and luminosity monitor
TOTEM-CMS
ATLAS
April 23, 2006
DIS2006
XIV International Workshop on Deep Inelastic Scattering
Tsukuba, Japan, 20-24/April/2006
11
totalcross
Cross-Section
pp pp
total
section
d el
dt

t o
1 dN el
L dt
t o
 1  r 2 
 tot 
 tot
16
1 r 2
N el  Ninel
1  r 2  N el  Ninel 
L
16  dN el / dt  t 0
2
N el  N inel 

 tot 
L
• Measure the total rate (Nel+Ninel) , diff ~ 18 mb
and min. bias ~65 mb, with an expected precision of
(running for 1 day at L = 1.6 x 1028cm-2s-1).
• Extrapolate the elastic cross-section to t = 0:
(M. Deile)
Luminosity-independent measurement using the Optical
Theorem:
16  dN el / dt  t 0
2
0.8 %
systematics dominated:
(statistical error after 1 day: 0.07 %)
0.5 %
• ρ =Re f(0)/Im f(0) unknown; using COMPETE pred.:
0.2 %
(r = 0.1361±0.0015
April 23, 2006
)
+0.0058
-0.0025
DIS2006
XIV International Workshop on Deep Inelastic Scattering
Tsukuba, Japan, 20-24/April/2006
1 % 12
pp total Cross-Section
• Current models
predictions: 90-130 mb
• Aim of TOTEM:
~1% accuracy (~1 mb)
[PRL 89 201801 (2002)]
Cudell et al.
COMPETE Collaboration
fits all available hadronic
data and predicts:
April 23, 2006
 4.1 mb


111
.
5

1
.
2
LHC: tot
 2.1
DIS2006
XIV International Workshop on Deep Inelastic Scattering
Tsukuba, Japan, 20-24/April/2006
13
ATLAS’s Plans:
ATLAS submitted a Letter of Intent to complement the experiment
with a set of forward detectors for luminosity measurement and
monitoring as part of a two stage scenario:
1. Short time scale
 Roman Pots at 240 m from IP1
• Probe the elastic scattering in the Coulomb interference
region
 Dedicated detector for luminosity monitoring – LUCID
• Used also to transfer the calibration from 1027 1034
Goal: Determine absolute luminosity at IP1
(2-3% precision)
2. Longer time scale
 Study opportunities for diffractive physics with ATLAS
 Propose a diffractive physics program using additional detectors
(I. Efthymiopoulos)
April 23, 2006
DIS2006
XIV International Workshop on Deep Inelastic Scattering
Tsukuba, Japan, 20-24/April/2006
14
Physics interest -- ATLAS
Luminosity Measurement – Why?
• Important for (precision)
comparison with theory:
 e.g. bb, tt, W/Z, n-jet, …
cross-section deviations
from SM could be a signal
for new physics
Systematic error dominated by
the luminosity measurement
(ATLAS-TDR-15, May 1999)
(I. Efthymiopoulos)
April 23, 2006
DIS2006
XIV International Workshop on Deep Inelastic Scattering
Tsukuba, Japan, 20-24/April/2006
15
pp elastic scattering
TOTEM
April 23, 2006
DIS2006
XIV International Workshop on Deep Inelastic Scattering
Tsukuba, Japan, 20-24/April/2006
16
Elastic scattering – from ISR to Tevatron
~1.5 GeV2
April 23, 2006
DIS2006
XIV International Workshop on Deep Inelastic Scattering
Tsukuba, Japan, 20-24/April/2006
17
pp elastic scattering cross-section
Photon - Pomeron interference  r
Multigluon (“Pomeron”) exchange  e– B |t|
104 per bin
of 10-3 GeV2
B(s) = B0 + 2aP’ ln (s/s0) ~ 20 GeV-2 at LHC
 t  p2 2
diffractive structure
pQCD
BSW = Bourrely,
Soffer and Wu
b* =
pp 14 TeV
BSW model
b*=18
1540 m
L = 1.6 x 1028 cm-2 s-1
m
L = 3.6 x 1032 cm-2 s-1
(1)
(3)
April 23, 2006
~ 1/|t|8
wide range of
predictions
-t [GeV2]
DIS2006
XIV International Workshop on Deep Inelastic Scattering
Tsukuba, Japan, 20-24/April/2006
~1 day
(1)
(3)
18
Elastic Scattering Models (eg. Islam et al)
Observations:
• fwd diffraction cross
section increases
•
• diffractive peak
shrinks
 1/t8
Islam et al
BSW
Desgrolard
et al
April 23, 2006
• interference dip moves
to smaller t
• at –t  1 GeV2:
• d/dt  1/t8
• (3-gluon exchange)
• little s dependence
DIS2006
XIV International Workshop on Deep Inelastic Scattering
Tsukuba, Japan, 20-24/April/2006
19
Elastic Scattering- el/tot
Rdiff=[el(s) +SD(s) + DD(s)]/tot(s)
Rel = el(s)/tot(s)
0.3
0.30
0.4
0.375
0.2
0.3
0.1
4
5
6
3
4
5
6
log(s/s0)
 el  30% of tot at the LHC ?
 SD + DD  10% of tot (= 100-150mb) at the LHC ?
April 23, 2006
DIS2006
XIV International Workshop on Deep Inelastic Scattering
Tsukuba, Japan, 20-24/April/2006
(M. Deile)
3
0.2
20
Low-x at the LHC
LHC: due to the high energy can reach
small values of Bjorken-x
in structure of the proton F(x,Q2)
Processes:
 Drell-Yan
 Prompt photon production
 Jet production
 W production
Proton structure at low-x !!
Parton saturation effects?
April 23, 2006
DIS2006
XIV International Workshop on Deep Inelastic Scattering
Tsukuba, Japan, 20-24/April/2006
(A. deRoeck)
If rapidities below 5 and
masses below 10 GeV can be
covered  x down to 10-6-10-7
Possible with T2 upgrade in TOTEM
(calorimeter, tracker) 5<h< 6.7 !
21
Diffractive physics
ALICE
TOTEM
CMS
F420 project
April 23, 2006
DIS2006
XIV International Workshop on Deep Inelastic Scattering
Tsukuba, Japan, 20-24/April/2006
22
Double Pomeron exchange:
Single diffraction:
X
p p  p X
2 gluon exchange with vacuum
quantum numbers
“Pomeron”
X
p p  p X p
Double diffraction:
X
Y
p p  X Y
April 23, 2006
DIS2006
XIV International Workshop on Deep Inelastic Scattering
Tsukuba, Japan, 20-24/April/2006
(M. Ruspa)
The accessible physics is a function
of the integrated luminosity
23
CMS + TOTEM: Acceptance
largest acceptance detector ever built at a hadron collider
90% (65%) of all diffractive protons are detected for b* = 1540 (90) m
107 min bias events, incl. all diffractive processes, in 1 day with b* =1540 m
T1,T2
T1,T2
Charged
particles
Roman Pots
Roman Pots
dNch/dh
Total TOTEM/CMS acceptance
b *=90m
ZDC
CMS
dE/dh
Energy flux
central
T1
HCal
TOTEM+CMS
RPs
T2
CASTOR
b *=1540m
Pseudorapidity: h = ln tg /2
April 23, 2006
DIS2006
XIV International Workshop on Deep Inelastic Scattering
Tsukuba, Japan, 20-24/April/2006
24
Soft Diffractive Event rates
DPE:
pp  pXp
Acc = 27.8%
for detecting both
protons (b* = 90 m)
April 23, 2006
ALICE is studying the
possibility of
implementing a trigger
requiring a rapidity
gap on both sides of a
central region of 1.5
units of rapidity. The
selection can include
EM energy deposition
in the PHOS, protons
in the HMPID (RICH),
or electrons identified
with the TRD, opening
the possibility to study
heavy flavour
production in double
diffractive events.
DIS2006
XIV International Workshop on Deep Inelastic Scattering
Tsukuba, Japan, 20-24/April/2006
25
diffractive system X
proton:p2’
DPE
rapidity gap
Dh2= – ln 2
hmin
proton:p1’
rapidity gap
Dh1= – ln 1
hmax
Events/GeV-day
Exchange of color singlets
(“Pomerons”)
 rapidity gaps Dh
Measure > 90 (65)% of leading
protons with RPs at b* = 1540 (90) m
and diffractive system X with T1, T2
and CMS.
Scenario
(2)
b* (m) = 1540
April 23, 2006
DIS2006
XIV International Workshop on Deep Inelastic Scattering
Tsukuba, Japan, 20-24/April/2006
(4)
90
26
Hard Diffractive Events
Diffractive events with high pT particles produced
Double pomeron Ex: pp  pjjXp
= 1 mb
pT > 10 GeV
Acc = 29.3% (for b* =90 m, prel.)
hard
M
hard
(V. Avati)
hard
Double
Pomeron
Exchange
M
Single diffraction: pp  p + 3j
u
p
g
p
April 23, 2006
g
d
u
jet 1 (pT 1)
jet 2 (pT 2)
jet 3 (pT 3)
p
DIS2006
XIV International Workshop on Deep Inelastic Scattering
Tsukuba, Japan, 20-24/April/2006
27
Exclusive Double Pomeron Exchange
p
TOTEM-CMS
FP420
(with ATLAS/CMS)
April 23, 2006
DIS2006
XIV International Workshop on Deep Inelastic Scattering
Tsukuba, Japan, 20-24/April/2006
H
p
28
Exclusive Double Pomeron Exchange
Quantum numbers are defined
for exclusive particle production
Gluonic states c , b , Higgs,
supersymmetric Higgs,…..
Motivation from KMR calculations (e.g. hep-ph 0111078)
MX2 = 1 2 s
• Selection rules mean that central system is (to a good approx) 0++
• H→b-bbar:
QCD b-bbar bkgd suppressed by Jz=0 selection rule
• If you see a new particle produced exclusively with proton tags you know
its quantum numbers
• Tagging the protons means excellent mass resolution (~ GeV) irrespective of
the decay products of the central system
• Proton tagging may be the discovery channel in certain regions of the
MSSM
Trigger studies were discussed by M. Ruspa
April 23, 2006
DIS2006
XIV International Workshop on Deep Inelastic Scattering
Tsukuba, Japan, 20-24/April/2006
29
SUSY Higgs:
h, H, A, (H+, H--)
Tasevsky et al
Diffractive: H bb
Yuk. coupling, DMH, 0++
L=60 fb-1
mH=160
mH=140
Inclusive:
H,A tt
wide bump
5
From A.
Martin’s
parallel
session talk
April 23, 2006
DIS2006
XIV International Workshop on Deep Inelastic Scattering
Tsukuba, Japan, 20-24/April/2006
30
From A. Martin’s parallel session talk
Alan’s Conclusions
There is a very strong case for installing proton taggers
at the LHC, far from the IP ---- it is crucial to get the
missing mass DM of the Higgs as small as possible
The diffractive Higgs signals beautifully complement the
conventional signals. Indeed there are significant SUSY
Higgs regions where the diffractive signals are advantageous
---determining DMH, Yukawa Hbb coupling, 0++ determinn
---searching for CP-violation in the Higgs sector
(pp  p + H + p) ~ 3 fb at LHC
for SM 120 GeV Higgs
•L(LHC)~60 fb-1
~10 observable events after cuts + efficiency
Higgs needs L ~ 1033 cm-2 s-1, i.e. a running scenario for b* = 0.5 m:
• trigger problems in the presence of overlapping events (see M. Ruspa’s talk)
• install additional Roman Pots in cold LHC region (420 m) at a later stage
April 23, 2006
DIS2006
XIV International Workshop on Deep Inelastic Scattering
Tsukuba, Japan, 20-24/April/2006
31
FP420 Project
The aim of FP420 is to install high precision silicon tracking and fast
timing detectors close to the beams at 420 m from ATLAS and/or CMS.
FP420 turns the LHC into a glue-glue collider where you know the beam
energy of the gluons to ~ 2 GeV.
With nominal LHC beam optics
@ 1033-34 cm-2s-1:
• 220 m: 0.02 <  < 0.2
• 420 m: 0.002 <  < 0.02
1 2 s = M2
With √s = 14TeV, MH = 120 GeV
on average:
  0.009  1%
Hence the need for FP420
(See B. Cox’s talk in the diffractive parallel session)
April 23, 2006
DIS2006
XIV International Workshop on Deep Inelastic Scattering
Tsukuba, Japan, 20-24/April/2006
32
Forward physics:
connection to cosmic rays
ALICE
TOTEM
LHCf
April 23, 2006
DIS2006
XIV International Workshop on Deep Inelastic Scattering
Tsukuba, Japan, 20-24/April/2006
33
Issues in UHE cosmic rays
1. Spectrum / GZK Cutoff
29th ICRC Pune
April 23, 2006
DIS2006
XIV International Workshop on Deep Inelastic Scattering
Tsukuba, Japan, 20-24/April/2006
34
Issues in UHE cosmic rays
Measurements of the very forward
energy flux (including diffraction)
and of the total cross section are
essential for the understanding of
cosmic ray events
p
Xmax(g/cm2)
2. Composition
Fe
At LHC pp energy:
Energy (eV)
> 107 events at the LHC in one day
April 23, 2006
DIS2006
XIV International Workshop on Deep Inelastic Scattering
Tsukuba, Japan, 20-24/April/2006
(O. Adriani)
104 cosmic events km-2 year-1
35
UHE Cosmic Rays
g
p
Fe
Cosmic ray
showers:
Dynamics of
the high
energy
particle
spectrum is
crucial
Interpreting cosmic ray data depends
on hadronic simulation programs
Forward region poorly known/constrained
Models differ by factor 2 or more
Need forward particle/energy measurements
e.g. dE/dh…
April 23, 2006
DIS2006
XIV International Workshop on Deep Inelastic Scattering
Tsukuba, Japan, 20-24/April/2006
36
Model Predictions: pp at the LHC
Predictions in the forward region within the CMS/TOTEM acceptance
April 23, 2006
DIS2006
XIV International Workshop on Deep Inelastic Scattering
Tsukuba, Japan, 20-24/April/2006
37
LHCf
Measurement of Photons and Neutral Pions
in the Very Forward Region of LHC
(O. Adriani)
Simulation of an
atmospheric shower due
to a 1019 eV proton.
• The dominant contribution to the energy flux is in the very forward
region
• In this forward region the highest energy measurements of 0 cross
section were done by UA7 (E=1014 eV, y = 5÷7)
The direct measurement of the  production cross section
as function of pT is essential to correctly estimate the
energy of the primary cosmic rays (LHC: 1017 eV)
April 23, 2006
DIS2006
XIV International Workshop on Deep Inelastic Scattering
Tsukuba, Japan, 20-24/April/2006
38
LHCf
Experimental Method:
2 independent detectors on both sides of IP
Detector I
Tungsten
Scintillator
Scintillating fibers
Detector II
Tungsten
Scintillator
Silicon mstrips
INTERACTION POINT
IP1 (ATLAS)
140 m
140 m
Beam line
•LHCf will cover up to y → ∞
April 23, 2006
DIS2006
XIV International Workshop on Deep Inelastic Scattering
Tsukuba, Japan, 20-24/April/2006
(O. Adriani)
•The vacuum tube contains two counterrotating beams. The beams transition from one
beam in each tube to two beams in the same
tube.
•Detectors will be installed in the TAN region,
140 m away from the Interaction Point, in front
of luminosity monitors
•Charged particle are swept away by magnets
39
Summary
There are plans at the LHC for a wide range of
Forward and Diffractive measurements that can be
achieved at a variety of different luminosities:
Measure total cross-section tot with a precision of 1%
Measure elastic scattering in the range 10-3 <|t|< 8 GeV2
A study of soft and hard diffractive physics:
 semi-hard diffraction (pT > 10 GeV)
 hard diffraction
 Inclusive DPE
Studies of Exclusive Double Pomeron Exchange events
Studies of very forward particle production
 Connection with UHE Cosmic ray phenomena
 Special exotics (centauro’s, DCC’s in the forward region)
April 23, 2006
DIS2006
XIV International Workshop on Deep Inelastic Scattering
Tsukuba, Japan, 20-24/April/2006
40
Extra slides
April 23, 2006
DIS2006
XIV International Workshop on Deep Inelastic Scattering
Tsukuba, Japan, 20-24/April/2006
41
Elastic Scattering: r = Re f(s,0)/Im f(s,0)
TOTEM
r Ref+(s,0)/Imf+(s,0)
(analyticity of the
scattering amplitude via
dispersion relations)
 constant/lns with s
April 23, 2006
DIS2006
XIV International Workshop on Deep Inelastic Scattering
Tsukuba, Japan, 20-24/April/2006
42
Pile-up: numbers!
PHOJET: ALL PROCESSES
NONDIF.INELASTIC
ELASTIC
DOUBLE POMERON
SINGLE DIFFR.(1)
SINGLE DIFFR.(2)
DOUBLE DIFFRACT.
110 mb
51 mb
33 mb
1.95 mb
7.66 mb
7.52 mb
9.3 mb
1 mb = 100 events/s
@ 10 29 cm-2 s-1
Number
Numberof
ofpileup
pileupevents
eventsper
perbunch
bunchcrossing
crossing==
==Lumi*
Lumi*cross
crosssection
section**bunch
bunchtime
timewidth
width**total
totallhc
lhcbunches
bunches//filled
filledbunches
bunches==
-28(m
-3 (b/mb)
-3 (b/mb)
==10
103434cm
cm-2-2ss-1-1**10
1044(cm^
(cm^22/m^
/m^22))**10
10-28
(m22//b)
b)**51
110
mbmb
* 10
* 10
* 25
* 25
(ns)
(ns)
* *
10
10-9-9(s/ns)
(s/ns)**3564
3564//2808
280817
35
Selection of diffractive events with
32  0 is valid in the central detector region, but must be corrected
This
 1x10
number
rapidity gap selection only possible
33 cm-2s-1,
for the elastic and diffractive cross section
in the forward
region!
at luminosities
below 10
 1x1033  3.5
where event pile-up is absent
 2x1033  7
April 23, 2006
DIS2006
XIV International Workshop on Deep Inelastic Scattering
Tsukuba, Japan, 20-24/April/2006
43
RP
T1 & T2
TOTEM Experiment
(symmetric about IP5)
April 23, 2006
DIS2006
XIV International Workshop on Deep Inelastic Scattering
Tsukuba, Japan, 20-24/April/2006
RP
44
FP420 Acceptance and Resolution
3 mm + 3 mm
3 mm
25 mm
30 mm
5 mm
7.5 mm
10 mm
22 mm
April 23, 2006
DIS2006
XIV International Workshop on Deep Inelastic Scattering
Tsukuba, Japan, 20-24/April/2006
MB apertures
45
Edgeless silicon detectors for the RP
Active edges: X-ray measurement
Signal (a.u.)
Signal [a.u.]
1.6
1.4
1.2
Add here photo of RP
1
0.8
Strip 1
5mm dead
area
0.6
0.4
Strip 2
0.2
0
0
10 planes/pot
50
100
150
200
250
300
350
400
Position (microns)
150 mm
Strip 1
Strip 2
Planar technology: Testbeam
40 mm dead area
active edges
(“planar/3D”)
April 23, 2006
10 mm dead area
50 mm dead area
66 mm pitch
planar technology CTS
(Curr. Termin. Struct.)
Detector 1
DIS2006
XIV International Workshop on Deep Inelastic Scattering
Tsukuba, Japan, 20-24/April/2006
Detector 2
46
Diffraction at b* = 1540 m Acceptance
RP at 220 m
Diffractive protons
are observed in a large
-t range:
=Dp/p; t=-(p)2
acc.
< 10%
April 23, 2006
90% are detected
-t > 2.5x10-3 GeV2
10-8 <  < 0.1
-3

resolution
~5x10
DIS2006
XIV International Workshop on Deep Inelastic Scattering
Tsukuba, Japan, 20-24/April/2006
47
Diffraction at b* = 90 m Acceptance
Resolution in :
 = 4x10-4
(prel.)
L<2x1031 cm-2s1
April 23, 2006
DIS2006
XIV International Workshop on Deep Inelastic Scattering
Tsukuba, Japan, 20-24/April/2006
48
Diffraction at b* = 0.5 m
April 23, 2006
DIS2006
XIV International Workshop on Deep Inelastic Scattering
Tsukuba, Japan, 20-24/April/2006
49