DD

DDØØ Forward Proton Detector Forward Proton Detector

Andrew BrandtAndrew BrandtUTAUTA

Q4D SQ3S

A1A2

P1UP

p p

Z(m)

D1

Detector

Bel

low

s

Roman Pot

233359 3323057

P2OUT

Q2

P1DN P2IND2Q4 Q3 Q2

June 23, 2002Atlas Collab. MeetingClermont-Ferrand

DDDiffraction Thesis Topics

Soft Diffraction and Elastic Scattering: Inclusive Single Diffraction

Elastic scattering (t dependence)

Total Cross Section

Centauro Search

Inclusive double pomeron

Search for glueballs/exotics

Hard Diffraction: Diffractive jet

Diffractive b,c

Diffractive W/Z

Diffractive photon

Diffractive top

Diffractive Higgs

Other hard diffractive topics

Double Pomeron + jets

Other Hard Double Pomeron topics

Rapidity Gaps: Central gaps+jets

Gap tags vs. proton tags

Double pomeron with gaps

E

<100 events in Run I, >1000tagged events in Run II

DDData Taking

• No special conditions required • Read out Roman Pot detectors for all events (can’t miss ) • A few dedicated global triggers for diffractive jets, double pomeron, and elastic events• Use fiber tracker trigger board -- select , |t| ranges at L1, readout DØ standard• Reject fakes from multiple interactions (Ex. SD + dijet) using L0 timing, silicon tracker, longitudinal momentum conservation, and scintillation timing• Obtain large samples (for 1 fb-1):

~ 1K diffractive W bosons ~ 3K hard double pomeron ~500K diffractive dijets

ttppp

with minimal impact on standard DØ physics program

DDAcceptanceQuadrupole ( p or )p

Dipole ( only)p

Dipole acceptance better at low |t|, large Cross section dominated by low |t| ||6/ tedtd

0 0.02 0.04 1.4 1.4 1.3 2 35 95

(%)AQuadrupole Dipole

MX (G

eV)

450

400

350

280

200

GeV2

GeV2

450

400

350

280

200

MX (G

eV)

Geo

met

ric

A

ccep

tan

ce

DD

• Constructed from 316L Stainless Steel• Parts are degreased and vacuum degassed• Plan to achieve 10-11 Torr• Use Fermilab style controls• Bakeout castle, then insert fiber detectors

Roman Pot Castle Design

Detector

50 l/s ion pump

Beam

Worm gear assembly

Step motor

DD

Thin windowand flangeassembly

Bellows

Detector is inserted into cylinder until it reaches thin window

Motor

Flangeconnectingto vacuum vessel

ThreadedCylinder

Roman Pot Arm Assembly

DDBypass

Sep SepSep

Sep Girder

TunnelFloor

Pit Floor

Bypass

Sep SepSep PotPot

Sep Girder

Pit FloorHole inFloor

Run II Girder Configuration

Run I Girder Configuration

Girder Reconfiguration

BEFORE:

AFTER:

p

p

DD

All 6 castles with 18 Roman pots comprising the FPD were constructed in Brazil, installed in the Tevatron in fall of 2000, and have been functioning as designed.

Quadrupole castle A2 installed in the beam line.

Castle StatusCastle Status

DD

4 fiber bundlefits well thepixel size ofH6568 16 Ch.MAPMT (Multi-Anode Photomultiplier Tube)7 PMT’s/detector16 250 m fibers each PMT

Six planes(u,u’,x,x’,v,v’)of 800 m scintillatingfibers (’) planesoffset by 2/3fiber

20 channels/plane(U,V)(’)16 channels/plane(X,X’)112 channels/detector18 detectors2016 total channels4 fibers/channel8064 fibers1 250 m LMB

fiber/channel8 LMB fibers / bundle252 LMB bundles80 m theoretical

resolution

Detector SetupDetector Setup

DD

At the University of Texas, Arlington (UTA), scintillating and optical fibers were spliced and inserted into the detector frames.

Detector AssemblyDetector Assembly

DD

The plastic frames containing the clear fibers are attached to the cartridge bottom.

Detectors in CartridgesDetectors in Cartridges

The cartridge bottom containing the detector is installed in the Roman pot and then the cartridge top with PMT’sis attached.

DD • All 18 cartridges have been assembled, 10 are installed in tunnel (8 with full detectors 2 with trigger scint). The 10 instrumented pots (Phase I) are ups, downs, and dipoles.

• Cables and tunnel electronics (low voltage, amp/shapers, etc.) installed and operational for full 18 pot (Phase II) setup.

• 9 more detectors are complete except for final polishing, last 3 (2 spares) will be finished this summer.

Tunnel and Detector StatusTunnel and Detector Status

DDIn the October 2001 shutdown four veto counters (designed at UTA, built at Fermilab) each of which cover 5.2 < || < 5.9 were installed between DØ and the first low beta quadrupole (Q4), about 6 m from the interaction point.

The counters, two each on the outgoing proton and anti-proton arms, can be used in Diffractive triggering (veto proton remnant).

Veto CountersVeto Counters

DDPot MotionPot Motion

Pot motion is controlled by an FPD shifter in the DØ Control Room via a Python program that uses the DØ online system to send commands to the step motors in the tunnel.

DDStand-alone DAQStand-alone DAQ

•Due to delays in DØ trigger electronics, we have maintained our stand-alone DAQ first used in the fall 2000 engineering run.

•We build the trigger with NIM logic using signals given by our trigger PMT’s, veto counters, DØ clock, and the luminosity monitor.

•If the event satisfies the trigger requirements, the CAMAC module will process the signal given by the MAPMT’s.

•With this configuration we can read the fiber information of only two detectors (currently PD spectrometer is read out), although all the trigger scintillators are available for triggering.

•An elastic trigger is formed from coincidences ofthe PU+AD spectrometers combined with halo vetoes (early time hits) and vetoes on LM and Veto counters.

DDFPD Control Room FPD Control Room

DDElastic Distribution (raw)

=p/p should peak at 0 for elastic events!!

Require clean events with 0 or 1 hit per plane for initial studies

DDData Elastic x,y Correlations

PD1x vs. PD2x (mm)

PD1y vs. PD2y (mm)

Good correlation between x1,x2 and y1,y2 in data but shifted from MC expectation (3 mm in x and 1 mm in y)

DDElastic ,t (calibrated)

Minimum t about 1.0 Gev2

peak reasonably Gaussian, still 2x ideal MC resolution

Calibrated now peaks at 0

DDProton IDProton ID

The Proton ID group led by Gilvan Alves and Sergio Novaes has made substantial progress in many software areas:

•Track reconstruction

•Monte Carlo

•Unpacking

•Single Interaction Tool

•Alignment

•Database

Regular Proton-ID meetings are held off-week Thursdays 11-12:30 in Black Hole using VRVS

DDGoals for 2002Goals for 2002

•Early summer •Installation of full readout chain for one spectrometer

•Late summer/fall•Installation of readout chain for Phase I 10 detectors = 5 spectrometers•FPD data acquisition integrated into DØ•Elastic + Diffractive dN/dt and -distribution

•September•FPD triggers in DØ global list

•December•First Diffractive + jets data analysis shown at QCD meeting

DDLessons LearnedLessons Learned

•Bigger project than you (I) might think: more manpower, time, cost, CABLES

•Using other people’s electronics is risky

•Need a budget and some level of priority (beyond the baseline syndrome)

•Early integration is essential

•Good contacts in the Accelerator Division are crucial

•Halo not well-understood

•Elastics or alignment, redundancy needed

•Splicing fibers is painful

DDFPD Summary• FPD will be a completely integrated sub-detector of the DØ detector which will help maximize Run II physics potential

• Hard diffraction exists, but not well-understood -- large data samples and precise measurements needed

• Large and L at Tevatron necessary for these measurements

• Combination of quadrupole and dipole spectrometers gives ability to tag both p’s and p ’s over large kinematic range, allows alignment, understanding of backgrounds

• Tremendous progress in installation and commissioning, emphasis switches to trigger, software, operations, and data analysis

• Starting to think about physics a little!

s

DD•Used finite element analysis to model different window options

•Built three types of pots and studied deflection with pressurized helium.

•150 micron foil with elliptical cutout gives excellent results

NIKHEF Window

DDMeasurements Using the FPD

• Observation of hard diffractive processes.• Measure cross sections

jetspp

jetsSD

allSD

jetsSD

dtdM

jetsSDd

2

2

02.0GeV280for%30012.0

01.0GeV200for%62/

M

MM

x

x

||12.0 tt dominated by angular dispersion 15% error for (resolutions given for dipole spectrometer).

• Measure kinematical variables with sensitivity to pomeron structure ( , ET, …) Use Monte Carlo to compare to different pomeron structures and derive pomeron structure.

• Combine different processes to extract quark and gluon content.

2GeV5.0|t|

DD

allSD

jetsSD

(Arbitrary Scale)

0.050

GeV15E t

0.050

GeV15E t

Dip

ole

Reg

ion

Qua

drup

ole

Reg

ion

FPD Measurements (1 fb-1)

DD

Et > 15 GeV10,000 events

Soft(1-x)5

Hardx(1-x)

jetspp

jetsSD

Et > 15 GeV0<|t|<3 GeV2

Hard gg

Hard qq

FPD Measurements (1 fb-1)

DDPot Motion SafeguardsPot Motion Safeguards

• The software is reliable and has been tested extensively. It has many safeguards to protect against accidental insertion of the pots into the beam.

• The drivers are disabled with a switch in the Control Room when the pots are not being moved.

• The pots are hooked to an emergency line which bypasses the software to send the pots back to the home position in case of emergency (tested but not used).

DDPot Insertion MonitorPot Insertion Monitor

Effect of the pot motion on the proton and antiproton losses at DØ and CDF is monitored using ACNET.

Current agreement with Beams Division and CDFrequires that the effect on halo rates is less than 20%.