Background model for a NaI (Tl) detector devoted to dark matter searches

NaI (Tl) Detectors is a well known high light yield scintillator. Very large crystals can be grown to be used in a wide range of applications. In particular, such large crystals are very good-performing detectors in the search for dark matter, where they have been used for a long time and reported first evidence of the presence of an annual modulation in the detection rate, compatible with that expected for a dark matter signal. In the frame of the ANAIS (Annual modulation with NaI Scintillators) dark matter search project, a large and long effort has been carried out in order to characterize the background of sodium iodide crystals.

Here we present in detail our background model for a 9.6 kg NaI (Tl) detector taking data at the Canfranc Underground Laboratory (LSC): most of the contaminations contributing to the background have been precisely identified and quantified by different complementary techniques such as HPGe spectrometry, discrimination of alpha particles vs. beta/gamma background by Pulse Shape Analysis (PSA) and coincidence techniques; then, Monte Carlo (MC) simulations using Geant4 package have been carried out for the different contributions.

Only a few assumptions are required in order to explain most of the measured background at high energy, supporting the goodness of the proposed model for the present ANAIS prototype whose background is dominated by 40K bulk contamination. At low energy, some non-explained background components are still present and additional work is required to improve background understanding, but some plausible background sources contributing in this range have been studied in this work. Prospects of achievable backgrounds, at low and high energy, for the ANAIS-upgraded detectors, relying on the proposed background model conveniently scaled, are also presented.

This article comes from sciencedirect edit released

Athermal lenses for thermography elements

Thermal cameras cannot use regular glass lenses, as glass will reflect thermal radiation rather than allowing the radiation to pass through the lenses. Commonly used materials for athermal lenses for thermography are Germanium (Ge), Chalcogenide glass, Zinc Selenide (ZnSe) and Zinc Sulfide (ZnS).

These materials provide good transmission for wavelengths in the range of 8-15um, i.e. LWIR (Long-wavelength infrared). Sometimes LWIR is also called far infrared.

The athermal lenses standard

Athermal lenses for thermography do not use C- or CS-mount lenses which are commonly used on standard cameras. Instead they use other types of mounts. The first documented thermal lens standard is TA-LENS. The letters “TA” stand for Thermal A, where “A” stands for the first documented standard.

Athermallenses provide a male thread which connects with a female thread on the camera. The thread is nominally 34 mm in diameter, with a pitch of two threads per mm (M34x0.5mm).

The athermal standard and an example of a athermal lens design

The lens mount is large enough for sensors with a diameter up to at least 13mm, which means that it works for commonly used LWIR sensors.

As the thread size is relatively large, it is possible to make adapters for other, smaller lenses for example lenses using M24x1 threads or M25x0.5mm threads.

Sample test chart images captured by an LWIR camera using (left) a 60 mm lens and (right) using a 10 mm. Both images are captured by a camera using the athermal lenses standard.

Long pass IPL glass filters

Long pass IPL glass filters are useful for selective wavelength absorption and therefore achieve high out of band blocking. Colour glass type Longpass filters have very low transmission in short wavelengths and high transmission in the long wavelengths. These filters are used in range of spectral selection scientific instrument applications.

The long-pass range of IPL glass filters listed here has uniform spectral transmission properties over their entire aperture. A wide range of Long pass IPL glass filters are available as 50x50mm and 25mm diameter filters, stocked in the options below.

Stock Long pass IPL glass filters are available to purchase directly from this website. To enquire about our customer colour glass capabilities, or to place a custom order, please contact our technical sales team.

This article comes from knightoptical edit released

General properties of LYSO(Ce) scintillator

LYSO (ce) crystal is a new type of scintillator crystal, it has excellent scintillation properties, like high light output, short decay time, also stable physical and mechanical properties, with high density and high Z value as well as strong anti-radiation hardness.

We have been optimizing the Czochralski technique to acquire LYSO(ce) crystal with larger dimension and better performance, now it can be produced at ∅90 mm x 200 mm length crystal blank in commercialized volume. Meanwhile, we have completed crystal further process equipment, including the line cutting and inner circle cutting machine as well as the grinding, polished and stable matrix assembly capability.

LYSO(ce) crystal is the ideal Positron Emission Tomography(PET) material, it has improved energy resolution and timing resolution compared with traditional BGO crystal, which is vital to get clear image and shorten the scanning procedure. According to authorized statistics, the global market for PET was estimated to be around 1G$, included the USA, Europe and Asia.

This article comes from epic-crystal edit released

MWIR Lenses – Infrared Optics with Low Distortion

MWIR Lenses is a family of midwave infrared lenses specifically designed to operate in the 3-5 ?m wavelenght region with InSb FPA Focal Plane Arrays. The MWIR Lenses offer a bayonet standard interface or, alternatively, they can be equipped with a custom mount interface at no additional cost.

In the MWIR lens design, great importance was attached to a good image quality and a large aperture (small F-number).

These MWIR lenses, mounted on a MWIR camera, are the perfect choice for a variety of applications, including imaging through fog, high-speed thermal imaging, thermography, R&D (MWIR range), non-destructive testing.

This article comes from stemmer-imaging edit released