A search for chameleon particles using a photon regeneration technique

We report the first results from the GammeV search for chameleon particles, which may be created via photon-photon interactions within a strong magnetic field. Chameleons are hypothesized scalar fields that could explain the dark energy problem. We implement a novel technique to create and trap the reflective particles within a jar and to detect them later via their afterglow as they slowly convert back into photons. These measurements provide the first experimental constraints on the couplings of chameleons to photons.Comment: 4 pages, 3 figures, accepted to PRL, minor revisions to introduction and a more quantitative estimate of reflection conditio

CMS physics technical design report : Addendum on high density QCD with heavy ions

Peer reviewe

Channel Control ASIC for the CMS hadron calorimeter front end readout module

The Channel Control ASIC (CCA) is used along with a custom Charge Integrator and Encoder (QIE) ASIC to digitize signals from the hybrid photo diodes (HPDs) and photomultiplier tubes (PMTs) in the CMS hadron calorimeter. The CCA sits between the QIE and the data acquisition system. All digital signals to and from the QIE pass through the CCA chip. One CCA chip interfaces with two QIE channels. The CCA provides individually delayed clocks to each of the QIE chips in addition to various control signals. The QIE sends digitized PMT or HPD signals and time slice information to the CCA, which sends the data to the data acquisition system through an optical link. (2 refs)

Thermal design and tests for the CMS HCAL readout box

A method is necessary to cool the electronics contained in the readout boxes for the CMS HCAL. The electronics to pre-amplify and digitize signals from the optical detectors will generate a large amount of heat that must be removed from the CMS HCAL system. To accomplish this a thermal management system has been designed that uses metallic extrusions, liquid coolant, and thermal foam to transfer the heat from the electronics to the exterior cooling system. Because the electronics are difficult to access throughout the life of the experiment, the temperature must be kept low to extend life expectancy. In order to test the concepts before the final design is implemented a thermal test station was built. Several methods to are under study to determine the best method of making the thermal routing from source of the heat to the liquid for heat removal. The test bed for this evaluation and methods to monitor the electronics temperature in situ will be discussed. 3 Refs

Front-end electro-optical interfaces for CMS HCAL

The CMS experiment is a complex instrument to study particle physics at the energy frontier. An important detector subsystem within CMS is the hadron calorimeter or HCAL, consisting of four subsystems that cover the kinematic region vertical bar eta vertical bar less than 5. This paper provides details of the electrooptical interfaces for the central barrel subsystem that operates in a region of high magnetic field and converts scintillation signals from megatile sampling layers to tower geometry for energy measurement. 3 Refs

Radiation validation for the CMS HCAL front-end electronics

Over a 10 year operating period, the CMS Hadron Calorimeter (HCAL) detector will be exposed to radiation fields of approximately 1 kRad of total ionizing dose (TID) and a neutron fluence of 4E11 n/cm/sup 2 /. All front-end electronics must be qualified to survive this radiation environment with no degradation in performance. In addition, digital components in this environment can experience single-event upset (SEU) and single-event latch-up (SEL). A measurement of these single-event effects (SEE) for all components is necessary in order to understand the level that will be encountered. Radiation effects in all electronic components of the HCAL front-end system have been studied. Results from these studies will be presented. (17 refs)