# Presentation: 280509

## Forward Calorimetry (HF)LHCC PresentationJanuary 24, 2000

**Nural Akchurin**
**HF Technical Coordinator**

## Forward Calorimeter (HF)

## HF Collaborators

**Hungary**
**KFKI- RMKI - Budapest**
**ATOMKI - Debrecen**
**Russia**
**ITEP- Moscow**
**Moscow State U.**
**VNIITF (Snezhinsk)**
**Turkey**
**Cukurova University - Adana**
**Middle East Technical University - Ankara**
**USA**
**Boston University**
**Fairfield University**
**University of Iowa**
**Iowa State University**
**Texas Tech University**

**Rapidity Coverage and E****t****miss**

**HF covers ~40% of phase space, 3 < ******** <5.**
**HF improves the E****t****miss****  resolution by ~30 %.**
- 10000 ISAJET background events
- 40 % min. bias and 60% two jet events
- ~25 *pp* interactions per crossing (*L *=  1034 cm-2 sec-1)

## Quartz Calorimeter Features

**The detector is radiation hard at the required level (100’s of MRad, steel and quartz)**
**Predominantly sensitive to the electromagnetic shower components (********M****, ********0****)**
**Cherenkov light cone (46****0****) from charged secondaries overlaps with the fiber numerical aperture (NA ~ 0.22)**
**Very fast pulse development (<10 ns)**
**Low but sufficient light yield (<0.5 pe/GeV)**
**Effects of induced activity and neutron flux to a great extent are absent**
**Neutron production is reduced (high-*****Z***** vs. low-*****Z*****)**
**The detector is short and hermetic**

## Experimental Technique

**Light is generated by Cherenkov effect in quartz fibers**
**Sensitive to relativistic charged particles (Compton electrons...)**
**d****2****N/dxd********=2********z****2****(sin****2********/********2****)**
**	****=(2********z****2****/ ********2 ****)[1-1/********2****n****2****]**
******min**** = 1/n**
**	********min**** ~ 200 keV**
**Amount of collected light depends on the angle between the particle path and the fiber axis**

## HF Transverse Segmentation

**3 < ******** < 5**
**HF is segmented in ******** = ******** = 0.175 (13 segments in rapidity and 10****0**** slices in the azimuth)**
**The active region extends from r=12.5 cm to 130 cm.  The depth is 165 cm (Fe).**

**QQ/QP Border**

## HF Longitudinal Segmentation

**2.5 mm**

**2.5 mm**

**TC (30 cm)**

**HAD (143 cm)**

**EM (165 cm)**

**HF Longitudinal Segmentation**

**   ****The fibers are located in a 2.5 mm by 2.5 mm square grid inside the steel absorber**

## HF Absorber Module

**HF Absorber Module**

**HF Module is the basic building block of the absorber.  It is low-carbon, soft steel and made out of 2 mm (blank) and 3 mm (grooved) thick plates.**

## 20-degree Wedge Structure

**20-degree sectors in absorber structure provides advantages over square units**
**Mechanical assembly is straight forward; the recent conceptual study finds no fundamental problems**
**The optical assembly (bundles and ferrules) is easier**
**It lends itself better for multiplexed fiber insertion operation at different stations and 20-degree wedge is the smallest unit for insertion operation**
**Source tube placement in the absorber is easier since a wedge is symmetric**
**The sector scheme requires more machining and welding.  The details are presently being studied.**

## PPP1 Parameters

**Absorber is iron (~9.5 ************)**
**Fibers are 300-micron dia QP**
**Fiber-to-fiber distance is 2.5 mm**
**Packing fraction is 0.85% for the “hadronic” section**
**Tower size is 6 cm x 6 cm (******** ~ 3.8)**
**Longitudinal segmentation is via fiber lenghts**
**EM = 165 cm**
**HAD = 143 cm**
**TC = 30 cm**
**R6427 PMTs (1-1/8”, 10-stage)**
**Calibration and monitoring**
**Radioactive source**
**LED and laser (337 nm)**

## Response to Electrons and Pions

**HF PPP1 responds linearly within 1% to electrons in the range tested (6 – 200 GeV).  The pion (neg) response is highly nonlinear.**

## Electromagnetic Energy Resolution

**Electromagnetic energy resolution is completely dominated by photostatistics (N****p.e.****).  The conventional parametrization, a/sqrt(E) + b, results in a~192% and b~9% for the PPP1.  0.85% fiber fraction degrades the EM energy resolution by a sqrt(2) compared to HAD95 (1.6%).**

**137%/sqrt(E) with **
**1.6% fiber packing**
**Fraction (HAD95)**

## Hadronic Energy Resolution

**Hadronic energy resolution is dominated by non-stochastic processes at higher energies.  Photo statistics becomes important only at lower energies.  The intrinsic energy resolution can be expressed as c-d*ln(E).  The expected energy resolution at 1 TeV is 18%.**

**Preliminary**

## Uniformity Scan with Electrons

**There is a +/- 6.5 % nonuniformity due to fiber periodicity at every 2.5 mm (5 mm for EM).**

## EM Shower Shape 

**Electromagnetic shower shape is quite narrow in quartz-fiber calorimeters compared to dE/dx type calorimeters because it employs Cherenkov signal.**

**47 mm**

## HF Absorber Requirements - I

**HF Absorber Requirements - I**

**The dead region between the modules need to be kept to a minimum.  The simulation suggests that the response to 1-TeV jets does not degrade appreciably up to ~8 mm of total distance between fiber rows (columns). **

**Module**

**Jet**

**Dead Region**

## HF Absorber Requirements - II

**The number of bad grooves or dead fibers, if randomly distributed, is not a fast varying function in resolution.  If a clumped set of grooves and/or fibers are damaged, the effect is much severer.**

## Fiber Packing Fraction

**Fiber Packing Fraction**

**The increase in the fiber fraction helps to increase the photon statistics.  If it is doubled, the EM resolution would be improved by a factor of 1/1.4.  The hadronic resolution is determined by non-stochastic processes and the gain is slight.  **

**Fiber Fraction 1%**

**Fiber Fraction 0.83%**

## Design Parameters

**Absorber material **
**Diffusion welded grooved steel plates**
**Quartz fiber packing fraction  **
**0.85 % ( 300-micron core dia. to 400-micron [1.5 %] )**
**All design parameters are such that 460-micron OD fiber can be substituted for 345-micron OD fiber **
**Fiber insertion into absorber**
**Requires 25 man-years for insertion by hand. Automatization studies are in progress now**
**Number of channels is 2484**
****** ****x ******** segmentation (0.175 x 0.175)**
**Outer radial dimension**
**130 cm from 140 cm (QQ/QP boundary is at ******** = 4)**

## HF Isometric View

**HF Isometric View**

**Calibration**
**      ****(US)**

**Luminosity**
**      ****(US)**

**  ****Assembly**
**(HU, RU, TR)**

**Readout Boxes**
**       ****(US)**

**Photodetectors**
**       ****(US)**

**Transporter**
**     ****(CP)**

**FE, Trig/DAQ**
**DCS, Voltage**
**     ****(US)**

**Shielding**
**    ****(CP)**

**Absorber**
**   ****(RU)**

**Optics**
**Quartz Fibers**
**US****, TR, HU,RU**

## Mechanics: Module Production Steps

**Mechanics: Module Production Steps**

**1**

**12**

**These steps were discussed in great detail during the Engineering Design Review (EDR) meeting in Dec. 1999.**

**The module production takes place in 12 basic steps from the acquisition of raw plates to the transportation of modules to CERN. **

## Mechanics: PPP Production

**Absorber is constructed from 2- and 3 mm plates.  3 mm thick plates are plastically deformed to allow for grooves on both sides.  **

**3 mm thick plate**

**~345 micron dia fiber**

## Mechanics: Diffusion Welding

**Diffusion welding is performed at 600 C for ~30 minutes.  It takes ~3 hours to reach this temperature and ~8 hours to cool down with forced argon circulation.  Typical pressure is 2x10****-4**** mmHg.**

## Mechanics: Sector Assembly - I

**Mechanical assembly starts with a self-contained wedge-shaped (20-degree sector) and assembled into a full half-detector.  Two quadrants have a locking mechanism.**

## Mechanics: Sector Assembly - II

**After one half is assembled, the top cradle is installed.  The concrete and polyethylene shielding matrix is bolted onto the cradle from outside.**

## Optics: Fibers

**QP (Quartz, Plastic)**
**Fused silica core, polymer cladding, UV-cured polymer buffer.**
**3234 km needed**
**N.A. = 0.37 +/- 0.02**

**QQ (Quartz, Quartz)**
**Fused silica core, fluorine-doped silicate cladding, polyimide buffer.**
**379 km needed**
**N.A. = 0.22 +/- 0.02**

**Buffer**

**Clad**

**Core**

## Optics: Wedge Fiber Bundles

**The 20-degree sector is optically independent.  All the fibers are cleaved and bundled to form towers at the PMT plate.  An air-core light guide transports light through the shielding matrix to the photomultipliers.**
**Cleaving vs polish**
**3M reflective material**

## Optics: Readout Box

**Each readout box houses 31 photomultiplers and a calibration unit which includes two blue LEDs, SMA connector for laser light input and two PIN photodiode signals to monitor light sources.  There is also a thermistor for temperature measurement.**

## Calibration with Cs137 Source

**The radioactive source will be used to transfer calibration from beam to each of the towers in HF.  It will also be used to monitor radiation damage to the fibers with time.**

## HF Radiation Environment

**Integration EDR_1**
**reviewed the status**
**of shielding **
**calculations and**
**design.**
**Activation levels**
**of steel will**
**be reviewed **
**today.**

**10****11**** n/cm****2**

**3 x 10****12**** n/cm****2**

**0.5 KRad**

**10 KRad**

**QQ/QP border**

## Radiation Damage

**Several quartz fiber irradiation studies have been carried out in the last several years.  The induced attenuation profile shows that there is less absorbtion in 400-500 nm (PMT) region compared to either shorter or longer wavelengths.**

**1 GRad**

**63% loss**

## ML1 and ML2 Milestones

**ML1 Milestones:**
**HF Inst and test in UX5 Complete****	****Jun 1 2005**
**ML2 Milestones:**
_**HF PPP1 absorber deliv. CERN  **__**	**__**Jul 15 1999**_
**HF EDR Complete****	****	****	****	****Oct 2 2000**
**Define fiber diameter****	****	****	****Jan 4 2001**
**Q1+Q2 Absorber delivered to CERN****	****Oct 15 2001**
**Q7+Q8 Absorber delivered to CERN****	****Jan 20 2003**
**HF Assembly in SX5 Complete****	****	****Feb18 2005**

## ML3 Milestones

_**HF Absorber Module EDR**__**	**__**	**__**Dec 2 1999**_
**HF Absorber Production Start****	****	****May 24 2000**
**HF ROBox Production Start****	****	****Apr 30 2001**
**HF- Support Frame Comp.****	****	****Mar 26 2001**
**HF Optics (fiber) procurement start****	****May 1 2001**
**HF+ Support Frame Comp.****	****	****Aug 13 2001**
**HF PMT procurement start****	****	****Oct 2 2001**
**HF Optics(fiber) inst into abs start****	****Nov 1 2001**
**Q3+Q4 Absorber delivered to CERN****	****Jan 14 2002**
**Q5+Q6 Absorber delivered to CERN****	****Dec 23 2002**

## ML3 Milestones (cont’d)

**HF Electronics in ROBoxes Complete****	****Sep 2 2003**
**HF ROBox Installation start****	****	****Dec 1 2003**
**HF Optics (fiber) inst in abs complete****	****Feb 2 2004**
**HF ROBox installation complete****	****May 12 2004**

**Include a Project chart from Mark...**

## CMS HF Organization

## Parameter Drawing

**Racks**

**Rotating Shield**

**RS/HF Collar**

**Muon System **
**Interface**

**Beam Pipe**

## EDR Conclusions: Manufacturing, Design and Assembly

**Concept of brick fixation must be developed taking seismic concerns**
**VNIITF seems technically competent**
**The source tube procedures must be detailed**
**Review of the external magnetic field and forces must be carried out**
**The general assembly scheme, up to the optical elements, must be defined**
**Describe assembly at CERN hall (Bat186), crane requirements and schedule**
**Describe maintenance scenario especially with respect to the radiation exposure**

## EDR Conclusions: General and Mechanical Safety; Optics

**No general problems except NDA (corrosion inhibitor)**
**Define the ultimate breaking value of the diffusion welded block**
**Provide Material Tables to R. Schmidt**
**Provide a cooling scheme for high luminosity (water pipes outside and conduction?)**
**Finalize Nitrogen circulation scheme (cooling, rust?)**
**Develop plans for dismantling and INB tractability**
**Investigate a semi-automatic insertion concepts**
**Investigation of alternative mechanical assembly techniques must take into account balance between mechanics and optics**
**The effect of NDA on the optical properties of the fiber must be investigated**
**Define goals (parameters) for fiber acceptance levels up to the optical bundling**

## EDR Conclusions: QA/QC and Organization

**Good system of Traveler**
**Non-conformity issues seem to be handled well (keep a non-conformity log-book)**
**External inspectors should have sufficient access to the manufacturing site**
**Define a maintenance plan for diffusion welding machine**
**Taveler will be in both (English and Russian) languages**
**Develop a QA/QC plan between VNIITF and CERN (acceptance criteria)**
**Good definition of operation sequence**
**Develop production plan and try to shorten the production time**
**Develop HF organization chart with responsibility and identify a general QA person**

## Summary and Conclusions

***Study the implications of square brick vs. sector bricks taking into account all implications.***
***Decide on the HF construction concept as soon as practically possible.***
***Launch a PPP2 in the light of the retained decision; in particular if a sector design is retained, PPP2 must be a sector brick.***
***Procure already enough material to manufacture PPP2 and possibly additional bricks.***
***Prepare for the next EDR, a general presentation comprising brick manufacture, assembly and fiber cabling, up to the fiber assembly in UX.***
**PPP1 was delivered according to schedule on July 1999 (ML2)**
**Beam test for PPP1 was carried out Sept 8, 1999.  The objectives were final fiber geometry, final longitudinal segmentation, near final photo detector, and calibration systems.**
**The experience from PPP1 suggests adequate physics performance.**
**The engineering will be carried out by Fermilab engineering team.**
**There is good progress in tooling at VNIITF and the production site is being developed. **
**Majority of the issues raised in the first EDR will be worked out by the end of May 2000.**

## US HF Organization

## HF Construction Strategy

**PMTs**
**Electronics**

**Fibers**

**Installation**
**Testing**

- CERN
- Bat 186

## Mechanics: HF Assembly Scenario

**Mechanics: HF Assembly Scenario**

**The modules are stacked together to form a half of the HF detector.  The modules will be preassembled to determine stacking tolerances.  The fibers are inserted into the modules before the final assembly.  Once a half detector is complete, the shielding can be installed around the detector.**

## HF Integration - I

**Rotating Shielding**
**Tolerances are compensated between HF and the rotating shielding; a shim will be fixed on the HF shielding; the maximum allowable gap is 3 cm.  RE (Integration EDR_1)**
**Beam Pipe**
**Vacuum conditioning equipment embedded inside the shielding behind HF.  HF opens into two halves to clear the beam pipe during installation and removal from nominal position **
**Endcap System**
**With the magnetic field off, the gap is 0.5 cm; with the field on, the gap will increase to 2 - 2.5 cm.  The exact seal is not yet determined (polyethylene ring)**
**Raiser Frames**
**HF is allowed to move in beam direction by 20 cm.  The correction for the beam height and angle are achieved by shimming.  HF rests on support frames when in beam position.**

## HF Integration - II

**TOTEM**
**Top of HF may serve as the installation platform.  The cables may pass in front of HF and the Endcap and will use the HF cable trays and patch panels.  It is necessary to remove TOTEM at every Endcap opening.  TOTEM (T1) is planned to be located in ********=3 cone**
**Alignment System**
**The alignment of HF to the cavern fiducial marks may provide sufficient control.  The transition of the alignment lines will be considered between Z +/- 21.6 m**
**Detector Assembly**
**The 80-tonne crane limit allows the lowering of half of the HF detector as a single unit to the experimental area.  The shielding elements are lowered separately and mounted onto the detector **

## HF Integration - III

**Access to the HF Platform**
**Proposal is to use the shielding ring at the back of YE3 as support for a horizontal passage from UX level 3 to connect to the lower level of HF platform**
**HF Electronics Racks**
**The position of the racks are in the minimum radiation zone according to the simulation results**
**HF Positioning**
**No remote movement of HF is possible; all systems are hard wired and have limit switches and mechanical stops.  In removing HF, first move by 20 cm in x (open detector); second open the shielding block to generate clearance in z; move HF by as much as +/- 20cm and lower HF using mechanical jacks and by removing support frames.  After removal of two frames, HF can be closed**

## HF Integration - IV

**HF Transporter Table**
**The support table is designed into the shielding to minimize the height of HF.  This allows the installation of a small overhead crane in the garage.  The crane capacity is to be determined  **
**HF Garage**
**The limited space in garage position allows 2x60 cm movement.  The access platforms need to be designed such that they can be folded if max opening is needed.  The access to the garage is at mid level.  The clearance between the sliding door and max Endcap opening is limited.  The Endcap winch system blocks the sliding door**
**TX Passage**
**TX passage between 12 meter pit (PM54) and detector cavern (UXC55) is 3.5 m in width.  The table and the detector absorber with support structure will fit through but the shielding assembly will have to be finalized in the cavern.  A guiding system will be designed to avoid sliding**